C-Plus-Plus | various algorithms in mathematics , machine learning | Learning library

 by   TheAlgorithms C++ Version: Current License: MIT

kandi X-RAY | C-Plus-Plus Summary

C-Plus-Plus is a C++ library typically used in Tutorial, Learning, Example Codes applications. C-Plus-Plus has no bugs, it has no vulnerabilities, it has a Permissive License and it has medium support. You can download it from GitHub.
This repository is a collection of open-source implementation of a variety of algorithms implemented in C++ and licensed under MIT License. These algorithms span a variety of topics from computer science, mathematics and statistics, data science, machine learning, engineering, etc.. The implementations and the associated documentation are meant to provide a learning resource for educators and students. Hence, one may find more than one implementation for the same objective but using a different algorithm strategies and optimizations.
    Support
      Quality
        Security
          License
            Reuse
            Support
              Quality
                Security
                  License
                    Reuse

                      kandi-support Support

                        summary
                        C-Plus-Plus has a medium active ecosystem.
                        summary
                        It has 23692 star(s) with 6190 fork(s). There are 485 watchers for this library.
                        summary
                        It had no major release in the last 6 months.
                        summary
                        There are 19 open issues and 235 have been closed. On average issues are closed in 108 days. There are 38 open pull requests and 0 closed requests.
                        summary
                        It has a neutral sentiment in the developer community.
                        summary
                        The latest version of C-Plus-Plus is current.
                        C-Plus-Plus Support
                          Best in #Learning
                            Average in #Learning
                            C-Plus-Plus Support
                              Best in #Learning
                                Average in #Learning

                                  kandi-Quality Quality

                                    summary
                                    C-Plus-Plus has 0 bugs and 0 code smells.
                                    C-Plus-Plus Quality
                                      Best in #Learning
                                        Average in #Learning
                                        C-Plus-Plus Quality
                                          Best in #Learning
                                            Average in #Learning

                                              kandi-Security Security

                                                summary
                                                C-Plus-Plus has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.
                                                summary
                                                C-Plus-Plus code analysis shows 0 unresolved vulnerabilities.
                                                summary
                                                There are 0 security hotspots that need review.
                                                C-Plus-Plus Security
                                                  Best in #Learning
                                                    Average in #Learning
                                                    C-Plus-Plus Security
                                                      Best in #Learning
                                                        Average in #Learning

                                                          kandi-License License

                                                            summary
                                                            C-Plus-Plus is licensed under the MIT License. This license is Permissive.
                                                            summary
                                                            Permissive licenses have the least restrictions, and you can use them in most projects.
                                                            C-Plus-Plus License
                                                              Best in #Learning
                                                                Average in #Learning
                                                                C-Plus-Plus License
                                                                  Best in #Learning
                                                                    Average in #Learning

                                                                      kandi-Reuse Reuse

                                                                        summary
                                                                        C-Plus-Plus releases are not available. You will need to build from source code and install.
                                                                        C-Plus-Plus Reuse
                                                                          Best in #Learning
                                                                            Average in #Learning
                                                                            C-Plus-Plus Reuse
                                                                              Best in #Learning
                                                                                Average in #Learning
                                                                                  Top functions reviewed by kandi - BETA
                                                                                  kandi's functional review helps you automatically verify the functionalities of the libraries and avoid rework.
                                                                                  Currently covering the most popular Java, JavaScript and Python libraries. See a Sample Here
                                                                                  Get all kandi verified functions for this library.
                                                                                  Get all kandi verified functions for this library.

                                                                                  C-Plus-Plus Key Features

                                                                                  The repository provides implementations of various algorithms in one of the most fundamental general purpose languages - C++.
                                                                                  Well documented source code with detailed explanations provide a valuable resource for educators and students alike.
                                                                                  Each source code is atomic using STL classes and no external libraries are required for their compilation and execution. Thus, the fundamentals of the algorithms can be studied in much depth.
                                                                                  Source codes are compiled and tested for every commit on the latest versions of three major operating systems viz., Windows, MacOS and Ubuntu (Linux) using MSVC 16 2019, AppleClang 11.0 and GNU 7.5.0 respectively.
                                                                                  Strict adherence to C++11 standard ensures portability of code to embedded systems as well like ESP32, ARM Cortex, etc. with little to no changes.
                                                                                  Self-checks within programs ensure correct implementations with confidence.
                                                                                  Modular implementations and OpenSource licensing enable the functions to be utilized conveniently in other applications.

                                                                                  C-Plus-Plus Examples and Code Snippets

                                                                                  No Code Snippets are available at this moment for C-Plus-Plus.
                                                                                  Community Discussions

                                                                                  Trending Discussions on C-Plus-Plus

                                                                                  Calculating the number of elements in an array using pointer arithmetic
                                                                                  chevron right
                                                                                  How to select a colored item from a bulleted list
                                                                                  chevron right
                                                                                  Why my loop, loop twice in Angular/TypeScript?
                                                                                  chevron right
                                                                                  up arrow, down arrow on a menu and hidden submenu
                                                                                  chevron right
                                                                                  arrow bottom in a menu en Angular/CSS
                                                                                  chevron right
                                                                                  Why is my title of my pages not positioned correctly?
                                                                                  chevron right
                                                                                  Why bootstrap distorts the menu in CSS?
                                                                                  chevron right
                                                                                  When making a shield.io badge, is there a way to find the right way to reference a logo name?
                                                                                  chevron right
                                                                                  Maybe and Either monads, short-circuiting, and performance
                                                                                  chevron right
                                                                                  Template specialization and references
                                                                                  chevron right

                                                                                  QUESTION

                                                                                  Calculating the number of elements in an array using pointer arithmetic
                                                                                  Asked 2021-Dec-11 at 23:40

                                                                                  I have come across a piece of example code that uses pointers and a simple subtraction to calculate the number of items in an array using C++.

                                                                                  I have run the code and it works but when I do the math on paper I get a different answer.

                                                                                  There explanation does not really show why this works and I was hoping someone could explain this too me.

                                                                                  #include 
                                                                                  using namespace std;
                                                                                  int main() {
                                                                                  int array[10] = {0, 9, 1, 8, 2, 7, 3, 6, 4, 5};
                                                                                  int stretch = *(&array + 1) - array;
                                                                                  cout << "Array is consists of: " << stretch << " numbers" << endl;
                                                                                  cout << "Hence, Length of Array is: " << stretch;
                                                                                  return 0;
                                                                                  }
                                                                                  

                                                                                  From: https://www.educba.com/c-plus-plus-length-of-array/

                                                                                  When I run the code I get the number 10.

                                                                                  When I print the results of *(&array + 1) and array by

                                                                                  cout << *(&array+1) << endl; cout << array << endl;
                                                                                  

                                                                                  I get of course two hex address's.

                                                                                  When I subtract these hex numbers I get 1C or 28???

                                                                                  Is it possible that C++ does not actually give the hex results or their translation to decimal but rather sees these numbers as addresses and therefore only returns the number of address slots remaining?

                                                                                  That is the closest I can come to an explanation if some one with more knowledge than I could explain this I would be very grateful.

                                                                                  ANSWER

                                                                                  Answered 2021-Dec-06 at 01:34

                                                                                  You forgot a small detail of how pointer addition or subtraction works. Let's start with a simple example.

                                                                                  int *p;
                                                                                  

                                                                                  This is pointing to some integer. If, with your C++ compiler, ints are four bytes long:

                                                                                  ++p;
                                                                                  

                                                                                  This does not increment the actual pointer value by 1, but by 4. The pointer is now pointing to the next int. If you look at the actual pointer value, in hexadecimal, it will increase by 4, not 1.

                                                                                  Pointer subtraction works the same way:

                                                                                  int *a;
                                                                                  int *b;
                                                                                  
                                                                                  // ...
                                                                                  size_t c=b-a;
                                                                                  

                                                                                  If the difference in the hexadecimal values of a and b is 12, the result of this subtraction will not be 12, but 3.

                                                                                  When I subtract these hex numbers I get 1C or 28 ???

                                                                                  There must've been a mistake with your subtraction. Your result should be 0x28, or 40 (most likely you asked your debugger or compiler to do the subtraction, you got the result in hexadecimal and assumed that it was decimal instead). That would be the ten ints you were looking for.

                                                                                  Source https://stackoverflow.com/questions/70239955

                                                                                  QUESTION

                                                                                  How to select a colored item from a bulleted list
                                                                                  Asked 2021-Dec-04 at 12:27

                                                                                  Here is my menu

                                                                                  If I click on Market for example, the background color must be in green.

                                                                                  I don't understand why the Currency and the Portfolio are in green?

                                                                                  In fact, the green background appears depending on the menu selected.

                                                                                  How can I solve this problem, please?

                                                                                  I think that the problem is perhaps here

                                                                                  admin.component.html

                                                                                  TS

                                                                                  export class AdminComponent implements OnInit {
                                                                                    selectedTab!: string;
                                                                                  
                                                                                    showSubmenu: any[] = [];
                                                                                    showInfo: any[] = [];
                                                                                  
                                                                                    menus: any[] = [
                                                                                      /* Market */
                                                                                      {
                                                                                        class: 'bx bx-grid-alt',
                                                                                        item: 'Market',
                                                                                        route: 'market',
                                                                                  
                                                                                        submenus: [
                                                                                          {
                                                                                            class: 'bx bx-box',
                                                                                            item: 'Item',
                                                                                            route: 'item',
                                                                                          },
                                                                                        ],
                                                                                      },
                                                                                  
                                                                                      /* Currency */
                                                                                  
                                                                                      {
                                                                                        class: 'bx bx-grid-alt',
                                                                                        item: 'Currency',
                                                                                        route: 'currency',
                                                                                      },
                                                                                  
                                                                                      /* Porfolio */
                                                                                  
                                                                                      {
                                                                                        class: 'bx bx-box',
                                                                                        item: 'Portfolio',
                                                                                        route: 'portfolio',
                                                                                  
                                                                                        submenus: [
                                                                                          {
                                                                                            class: 'bx bx-grid-alt',
                                                                                            item: 'Element',
                                                                                            route: 'element',
                                                                                          },
                                                                                        ],
                                                                                      },
                                                                                    ];
                                                                                  

                                                                                  I share you my code here.

                                                                                  Thank you very much for your help.

                                                                                  ANSWER

                                                                                  Answered 2021-Dec-04 at 12:27

                                                                                  You just need to change like this:

                                                                                  HERE your stackblitz corrected.

                                                                                  Source https://stackoverflow.com/questions/70221917

                                                                                  QUESTION

                                                                                  Why my loop, loop twice in Angular/TypeScript?
                                                                                  Asked 2021-Dec-03 at 22:32

                                                                                  To keep it simple, I created a menu and all of my bullet lists are stored in an array.

                                                                                  My problem is that when I run the loop it shows me 2 times, the same values ?? I do not understand why?

                                                                                  I think that the problem is in the HTML file?

                                                                                  admin.component.html

                                                                                  TS

                                                                                  export class AdminComponent implements OnInit {
                                                                                    showSubmenu: any[] = [];
                                                                                  
                                                                                    menus: any[] = [
                                                                                      {
                                                                                        item: 'Market',
                                                                                        submenus: [{ item: 'Item' }],
                                                                                      },
                                                                                      {
                                                                                        item: 'Portfolio',
                                                                                        submenus: [{ item: 'Element' }],
                                                                                      },
                                                                                    ];
                                                                                  
                                                                                    constructor() {}
                                                                                  
                                                                                    ngOnInit() {}
                                                                                  
                                                                                    toggleMenu(index: number) {
                                                                                      this.showSubmenu[index] = !this.showSubmenu[index];
                                                                                    }
                                                                                  }
                                                                                  

                                                                                  I can not retrieve the index of each array? I can do this? If so... How, please?

                                                                                  https://stackblitz.com/edit/angular-ivy-9ytvbk?file=src/app/admin/admin.component.html

                                                                                  QUESTION

                                                                                  up arrow, down arrow on a menu and hidden submenu
                                                                                  Asked 2021-Dec-03 at 01:16

                                                                                  I would like to create a menu with a down arrow like this:

                                                                                  illustration - 1

                                                                                  When I click on Market, a submenu is shown, and the arrow is up.

                                                                                  illustration - 2

                                                                                  I don't understand how to I can get this same result.

                                                                                  my menu

                                                                                  admin.component.html

                                                                                  
                                                                                    
                                                                                      
                                                                                      Menu
                                                                                    
                                                                                    
                                                                                    
                                                                                  
                                                                                  
                                                                                    
                                                                                      
                                                                                        
                                                                                        Dashboard
                                                                                      
                                                                                    
                                                                                    
                                                                                  
                                                                                  

                                                                                  admin.component.ts

                                                                                  export class AdminComponent implements OnInit {
                                                                                    constructor() {}
                                                                                  
                                                                                    elementMenu: boolean = false;
                                                                                    selectedTab!: string;
                                                                                  
                                                                                    ngOnInit() {}
                                                                                  
                                                                                    selectElementMenu() {
                                                                                      this.elementMenu = !this.elementMenu;
                                                                                    }
                                                                                  }
                                                                                  

                                                                                  The code is on Stackblitz

                                                                                  I thank you in advance for your help.

                                                                                  ANSWER

                                                                                  Answered 2021-Dec-02 at 13:35

                                                                                  Simply use *ngIf to conditionally render icon

                                                                                  Market
                                                                                  
                                                                                  
                                                                                  

                                                                                  Source https://stackoverflow.com/questions/70200230

                                                                                  QUESTION

                                                                                  arrow bottom in a menu en Angular/CSS
                                                                                  Asked 2021-Dec-02 at 12:11

                                                                                  I would like to add a down arrow for each li `at the right.

                                                                                  Here is an idea of the menu.

                                                                                  menu

                                                                                  How to I create the arrow, please? I have to use an image?

                                                                                  I can you provide my code below:

                                                                                  admin.component.html

                                                                                  
                                                                                    
                                                                                      
                                                                                      Menu
                                                                                    
                                                                                    
                                                                                    
                                                                                  
                                                                                  
                                                                                    
                                                                                      
                                                                                        
                                                                                        Dashboard
                                                                                      
                                                                                    
                                                                                    
                                                                                  
                                                                                  

                                                                                  styles.css

                                                                                  .sidebar .nav-links {
                                                                                    padding: 0;
                                                                                  }
                                                                                  
                                                                                  .sidebar .nav-links li {
                                                                                    position: relative;
                                                                                    list-style: none;
                                                                                    height: 50px;
                                                                                  }
                                                                                  
                                                                                  .sidebar .nav-links li a {
                                                                                    height: 100%;
                                                                                    width: 100%;
                                                                                    display: flex;
                                                                                    align-items: center;
                                                                                    text-decoration: none;
                                                                                    transition: all 0.4s ease;
                                                                                  }
                                                                                  
                                                                                  .sidebar .nav-links li a:hover {
                                                                                    background: #081d45;
                                                                                  }
                                                                                  
                                                                                  .sidebar .nav-links li i {
                                                                                    min-width: 60px;
                                                                                    text-align: center;
                                                                                    font-size: 18px;
                                                                                    color: #fff;
                                                                                  }
                                                                                  
                                                                                  .sidebar .nav-links li a .links_name {
                                                                                    color: #fff;
                                                                                    font-size: 15px;
                                                                                    font-weight: 400;
                                                                                    white-space: nowrap;
                                                                                    text-transform: uppercase;
                                                                                  }
                                                                                  
                                                                                  .sidebar .nav-links li a:hover,
                                                                                  .selected {
                                                                                    background: #081d45;
                                                                                  }
                                                                                  

                                                                                  ANSWER

                                                                                  Answered 2021-Dec-02 at 12:11

                                                                                  You may use icons as font with adding to your project instead of using them separated images. I think best option for angular project is material icons.

                                                                                  angular material website

                                                                                  full icon list of material icons

                                                                                  You may also check for font awesome.

                                                                                  Source https://stackoverflow.com/questions/70198801

                                                                                  QUESTION

                                                                                  Why is my title of my pages not positioned correctly?
                                                                                  Asked 2021-Nov-29 at 10:43

                                                                                  I have a component named admin.component, in this component, I have a menu and a header.

                                                                                  In fact, when I create a new page, for example: the currency page.

                                                                                  The title is at the bottom of the la page, I don't understand why?

                                                                                  Normally, the title must be at the top...

                                                                                  I think that the component admin.component.html isnt't correct?

                                                                                    
                                                                                      
                                                                                        
                                                                                        Menu
                                                                                      
                                                                                      
                                                                                    
                                                                                    
                                                                                    
                                                                                      
                                                                                        
                                                                                          
                                                                                          Dashboard
                                                                                        
                                                                                        
                                                                                          
                                                                                          
                                                                                        
                                                                                        
                                                                                          Prem Shahi
                                                                                          
                                                                                        
                                                                                      
                                                                                    
                                                                                  

                                                                                  For the currency.component.html page, I have this:

                                                                                  
                                                                                    Currency Page
                                                                                  
                                                                                  

                                                                                  The code is available here, if you wish.

                                                                                  ANSWER

                                                                                  Answered 2021-Nov-29 at 10:43

                                                                                  It's working now need to change in admin.component.html with below stracture and resolved issue easily

                                                                                  
                                                                                    
                                                                                      
                                                                                        
                                                                                        Menu
                                                                                      
                                                                                      
                                                                                    
                                                                                    
                                                                                    
                                                                                      
                                                                                        
                                                                                          
                                                                                          Dashboard
                                                                                        
                                                                                        
                                                                                          
                                                                                          
                                                                                        
                                                                                        
                                                                                          Prem Shahi
                                                                                          
                                                                                        
                                                                                      
                                                                                      
                                                                                    
                                                                                  
                                                                                  

                                                                                  only add after tag and check upper code so you will get idea how to implement

                                                                                  Top Header is now fixed and only content will be change like below ss

                                                                                  Source https://stackoverflow.com/questions/70148073

                                                                                  QUESTION

                                                                                  Why bootstrap distorts the menu in CSS?
                                                                                  Asked 2021-Nov-27 at 21:22

                                                                                  I have a perfect menu in HTML/CSS

                                                                                  My problem is that bootstrap distorts the menu when I add the link Bootstrap.

                                                                                  
                                                                                  

                                                                                  I don't understand why I have this problem, please?

                                                                                  @import url('https://fonts.googleapis.com/css2?family=Poppins:wght@200;300;400;500;600;700&display=swap');
                                                                                  * {
                                                                                      margin: 0;
                                                                                      padding: 0;
                                                                                      box-sizing: border-box;
                                                                                      font-family: 'Poppins', sans-serif;
                                                                                  }
                                                                                  
                                                                                  .sidebar {
                                                                                      position: fixed;
                                                                                      height: 100%;
                                                                                      width: 240px;
                                                                                      background: #0a2558;
                                                                                      transition: all 0.5s ease;
                                                                                  }
                                                                                  
                                                                                  .sidebar.active {
                                                                                      width: 60px;
                                                                                  }
                                                                                  
                                                                                  .sidebar .logo-details {
                                                                                      height: 80px;
                                                                                      display: flex;
                                                                                      align-items: center;
                                                                                  }
                                                                                  
                                                                                  .sidebar .logo-details i {
                                                                                      font-size: 28px;
                                                                                      font-weight: 500;
                                                                                      color: #fff;
                                                                                      min-width: 60px;
                                                                                      text-align: center;
                                                                                  }
                                                                                  
                                                                                  .sidebar .logo-details .logo_name {
                                                                                      color: #fff;
                                                                                      font-size: 24px;
                                                                                      font-weight: 500;
                                                                                  }
                                                                                  
                                                                                  .sidebar .nav-links {
                                                                                      margin-top: 10px;
                                                                                  }
                                                                                  
                                                                                  .sidebar .nav-links li {
                                                                                      position: relative;
                                                                                      list-style: none;
                                                                                      height: 50px;
                                                                                  }
                                                                                  
                                                                                  .sidebar .nav-links li a {
                                                                                      height: 100%;
                                                                                      width: 100%;
                                                                                      display: flex;
                                                                                      align-items: center;
                                                                                      text-decoration: none;
                                                                                      transition: all 0.4s ease;
                                                                                  }
                                                                                  
                                                                                  .sidebar .nav-links li a.active {
                                                                                      background: #081d45;
                                                                                  }
                                                                                  
                                                                                  .sidebar .nav-links li a:hover {
                                                                                      background: #081d45;
                                                                                  }
                                                                                  
                                                                                  .sidebar .nav-links li i {
                                                                                      min-width: 60px;
                                                                                      text-align: center;
                                                                                      font-size: 18px;
                                                                                      color: #fff;
                                                                                  }
                                                                                  
                                                                                  .sidebar .nav-links li a .links_name {
                                                                                      color: #fff;
                                                                                      font-size: 15px;
                                                                                      font-weight: 400;
                                                                                      white-space: nowrap;
                                                                                  }
                                                                                  
                                                                                  .sidebar .nav-links .log_out {
                                                                                      position: absolute;
                                                                                      bottom: 0;
                                                                                      width: 100%;
                                                                                  }

                                                                                  ANSWER

                                                                                  Answered 2021-Nov-27 at 21:11

                                                                                  you can try this :

                                                                                  .sidebar .nav-links 
                                                                                      {
                                                                                                padding: 0;
                                                                                      }
                                                                                  

                                                                                  Source https://stackoverflow.com/questions/70138542

                                                                                  QUESTION

                                                                                  When making a shield.io badge, is there a way to find the right way to reference a logo name?
                                                                                  Asked 2021-Feb-12 at 12:28

                                                                                  I just started trying to use shield.io badges today. I'm a little confused.

                                                                                  When I needed to use the C++ logo in a label I used the following request:

                                                                                  https://img.shields.io/badge/C++-%2300599C.svg?&style=for-the-badge&logo=c%2B%2B&logoColor=white
                                                                                  

                                                                                  Which yielded a label with a logo, as intended.

                                                                                  I expected it to be logo=c-plus-plus and through trial and error I eventually found out that I should use the encoding for the + sign, %2B.

                                                                                  Now I can't find the logo for Selenium, although it is clearly on the simple-vector list (https://simpleicons.org/icons/selenium.svg) and there's nothing odd about this name, no spaces or signs, so I don't know how to find it. logo=selenium should work but it doesn't.

                                                                                  This is what I'm trying: https://img.shields.io/badge/selenium-%2343B02A.svg?&style=for-the-badge&logo=selenium&logoColor=white And what I get is a label without logo. Any thoughts?

                                                                                  PS: I don't have enough reputation to post images so I can't include the resulting images in the text but you can copy the link to see what I mean.

                                                                                  ANSWER

                                                                                  Answered 2021-Feb-12 at 12:28

                                                                                  Somehow it works now and I haven't changed anything in the code. Yay (?)

                                                                                  This will probably happen again.

                                                                                  Source https://stackoverflow.com/questions/65777962

                                                                                  QUESTION

                                                                                  Maybe and Either monads, short-circuiting, and performance
                                                                                  Asked 2020-Sep-17 at 19:32

                                                                                  Functional Programming in C++, at page 214, with reference to an expected monad which is the same as Haskell's Either, reads

                                                                                  [...] as soon as any of the functions you're binding to returns an error, the execution will stop and return that error to the caller.

                                                                                  Then, in a caption just below, it reads

                                                                                  If you call mbind [equivalent to Haskell's >>=] on an expected that contains an error,, mbind won't even invoke the transformation function; it will just forward that error to the result.

                                                                                  which seems to "adjust" what was written earlier. (I'm pretty sure that either LYAH or RWH underlines somewhere that there's no short-circuiting; if you remember where, please, remind me about it.)

                                                                                  Indeed, my understanding, from Haskell, is that in a chain of monadic bindings, all of the bindings happen for real; then what they do with the function passed to them as a second argument, is up to the specific monad.

                                                                                  In the case of Maybe and Either, when the bindings are passed a Nothing or Left x argument, then the second argument is ignored.

                                                                                  Still, in this specific two cases, I wonder if there's a performance penalty in doing something like this

                                                                                  justPlus1 = Just . (+1)
                                                                                  turnToNothing = const Nothing
                                                                                  Just 3 >>= turnToNothing >>= justPlus1 >>= justPlus1 >>= justPlus1 >>= justPlus1 >>= justPlus1
                                                                                  

                                                                                  as in these cases the chain can't really do anything other than what it does, given that

                                                                                  Nothing >>= _ = Nothing
                                                                                  Left l >>= _ = Left l
                                                                                  

                                                                                  ANSWER

                                                                                  Answered 2020-Sep-17 at 19:32

                                                                                  Consider the following expression:

                                                                                  result :: Maybe Int
                                                                                  result = x >>= f >>= g >>= h
                                                                                  

                                                                                  In that expression, of course, x :: Maybe a for some a, and each of f, g, and h are functions, with h returning Maybe Int but the intermediate types of the pipeline could be anything wrapped in a Maybe. Perhaps f :: String -> Maybe String, g :: String -> Maybe Char, h :: Char -> Maybe Int.

                                                                                  Let's make the associativity explicit as well:

                                                                                  result :: Maybe Int
                                                                                  result = ((x >>= f) >>= g) >>= h
                                                                                  

                                                                                  To evaluate the expression, each bind (>>=) must in fact be called, but not necessarily the functions f, g, or h. Ultimately the bind to h needs to inspect its left-hand argument to decide whether it is Nothing or Just something; in order to determine that we need to call the bind to g, and to decide that we need to call the bind to f, which must at least look at x. But once any one of these binds produces Nothing, we pay only for checking Nothing at each step (very cheap), and not for calling the (possibly expensive) downstream functions.

                                                                                  Suppose that x = Nothing. Then the bind to f inspects that, sees Nothing, and doesn't bother to call f at all. But we still need to bind the result of that in order to know if it's Nothing or not. And this continues down the chain until finally we get result = Nothing, having called >>= three times but none of the functions f, g, or h.

                                                                                  Either behaves similarly with Left values, and other monads may have different behaviors. A list may call each function one time, many times, or no times; the tuple monad calls each function exactly once, having no short-circuiting or other multiplicity features.

                                                                                  Source https://stackoverflow.com/questions/63943706

                                                                                  QUESTION

                                                                                  Template specialization and references
                                                                                  Asked 2020-Sep-10 at 06:36

                                                                                  In Functional programming in C++, chapter 11 deals with some basic template meta programming.

                                                                                  In this context, the author shows this implementation of remove_reference/remove_reference_t, which are essentially the same as those described on cppreference.

                                                                                  template struct remove_reference      { using type = T; };
                                                                                  template struct remove_reference  { using type = T; };
                                                                                  template struct remove_reference { using type = T; };
                                                                                  template using remove_reference_t = typename remove_reference::type;
                                                                                  

                                                                                  With reference to the code above, the author comments that when "calling" remove_reference_t, only the general (or primary? What is the correcto word here?) template successfully substitutes T, and the other two fail. This is clear to me, there's no way int can be written as/matched against T& or T&&.

                                                                                  As regards remove_reference_t, however, the author says that the second specialization cannot match. Well, couldn't it be a match thanks to reference collapsing? I mean, can't T&& match int& if I substitute T for int&, thus getting int&&& == int&?

                                                                                  Similarly, when calling remove_reference_t, can't the first specialization's T& match int&& if T is substituted for int&? (Why in the world did I think that & & would collapse to && instead of &?)

                                                                                  What makes the compiler discard one specialization?

                                                                                  ANSWER

                                                                                  Answered 2020-Sep-08 at 22:27

                                                                                  only the general (or primary? What is the correcto word here?) template

                                                                                  The technical term used by the C++ Standard is "primary class template". It will also be the most general class template, compared to its partial specializations and explicit specializations. So that could also be a reasonable thing to call it, given enough context.

                                                                                  The "reference collapsing rule" is found in [dcl.ref]/6 and applies mainly when determining the meaning of combining a specific type name which aliases a reference type with a & or && token which would normally form a reference to the type name's type. Deducing template arguments for a template parameter of the form T& or T&& is sort of the reverse of that. Although it's helpful to think of template argument deduction as "find the template arguments so that the resulting types match up", the technical details of template argument deduction are much more specific; [temp.deduct] is several pages of rules for exactly how this deduction proceeds, and there are additional relevant rules in other sections. The detail is needed so compilers agree on cases when there could otherwise be more than one "correct" answer, and so that compilers aren't required to deal with some of the more difficult cases.

                                                                                  In particular, when matching a dependent type P with a known type A, by the list of deducible types in [temp.deduct.type]/8, deduction can occur if both P and A have the form T& or if both have the form T&&. When attempting argument deduction for the partial specialization remove_reference to determine the definition of remove_reference, P is T&& and A is int&, so they do not share one of these forms.

                                                                                  The template argument deduction rules do not have a general allowance for deducing arguments from a reverse of the reference collapsing rule. But they do have a limited allowance which is related for certain cases: Per [temp.deduct.call]/3, if T is a template type parameter, but not a parameter for a class template, then the type T&& is a forwarding reference. When comparing types for argument deduction, if P=T&& is a forwarding reference type and A is an lvalue reference type, then the template type parameter T can be deduced as the lvalue reference type A, only if A is the type of an lvalue function argument expression ([temp.deduct.call]/3 again) or sometimes if P and A are being compared because they represent function parameter types within two compared function types ([temp.deduct.type]/10).

                                                                                  Similarly, when ["]calling["] remove_reference_t, can't the first specialization's T& match int&& if T is substituted for T&?

                                                                                  In this case, there's no possible way that the partial specialization remove_reference can match remove_reference. Even if the process of template argument deduction allowed finding a potential answer for this case, there is no possible type T such that T& is the same as int&&.

                                                                                  Source https://stackoverflow.com/questions/63801580

                                                                                  Community Discussions, Code Snippets contain sources that include Stack Exchange Network

                                                                                  Vulnerabilities

                                                                                  No vulnerabilities reported

                                                                                  Install C-Plus-Plus

                                                                                  You can download it from GitHub.

                                                                                  Support

                                                                                  Online Documentation is generated from the repository source codes directly. The documentation contains all resources including source code snippets, details on execution of the programs, diagrammatic representation of program flow, and links to external resources where necessary. The documentation also introduces interactive source code with links to documentation for C++ STL library functions used. Click on Files menu to see the list of all the files documented with the code. Documentation of Algorithms in C++ by The Algorithms Contributors is licensed under CC BY-SA 4.0.
                                                                                  Find more information at:
                                                                                  Find, review, and download reusable Libraries, Code Snippets, Cloud APIs from over 650 million Knowledge Items
                                                                                  Find more libraries
                                                                                  Explore Kits - Develop, implement, customize Projects, Custom Functions and Applications with kandi kits​
                                                                                  Save this library and start creating your kit
                                                                                  CLONE
                                                                                • HTTPS

                                                                                  https://github.com/TheAlgorithms/C-Plus-Plus.git

                                                                                • CLI

                                                                                  gh repo clone TheAlgorithms/C-Plus-Plus

                                                                                • sshUrl

                                                                                  git@github.com:TheAlgorithms/C-Plus-Plus.git

                                                                                • Share this Page

                                                                                  share link

                                                                                  Explore Related Topics

                                                                                  Reuse Pre-built Kits with C-Plus-Plus

                                                                                  Consider Popular Learning Libraries

                                                                                  freeCodeCamp

                                                                                  by freeCodeCamp

                                                                                  CS-Notes

                                                                                  by CyC2018

                                                                                  Python

                                                                                  by TheAlgorithms

                                                                                  interviews

                                                                                  by kdn251

                                                                                  Try Top Libraries by TheAlgorithms

                                                                                  Python

                                                                                  by TheAlgorithmsPython

                                                                                  Java

                                                                                  by TheAlgorithmsJava

                                                                                  JavaScript

                                                                                  by TheAlgorithmsJavaScript

                                                                                  Javascript

                                                                                  by TheAlgorithmsJavaScript

                                                                                  C

                                                                                  by TheAlgorithmsC

                                                                                  Compare Learning Libraries with Highest Support

                                                                                  Find, review, and download reusable Libraries, Code Snippets, Cloud APIs from over 650 million Knowledge Items
                                                                                  Find more libraries
                                                                                  Explore Kits - Develop, implement, customize Projects, Custom Functions and Applications with kandi kits​
                                                                                  Save this library and start creating your kit