Bookshop | simple Android project on BookShop Automation System

I made an application that makes some operations with MySQL and to give to the user the possibility of choiche which operation he can do, I create a menù loop with several choices. Here the code:

I want to write a function search :: String -> Char -> [Int] that returns the positions of all occurrences of the second argument in the first. For example:

I want to write a function search :: String -> Char -> [Int] that returns the positions of all occurrences of the second argument in the first. For example:

*i Want to get from the user his address and store it in file.dat then display these data
For Example:

so i am just a begineer who started learning reactJS i wrote below code to display a output but its showing blank page can some one please correct my code and tell me whats wrong why its showing blank page

The first time I used XAMPP, I created a folder named E_Shop and ever since I hit localhost or 127.0.0.1 in my URL address bar of my browser, I am directed to this E_Shop folder I created once,

now I have created another folder named PHP_execises in the same location I created E_Shop, in the htdocs folder of XAMPP folder, and I created a PHP file inside PHP_exercises, and here is the problem as you might guess: In the URL bar of the browser, hitting localhost/PHP_exercises pops an URL error, and hitting localhost alone, directs me to the E_Shop folder as default, and not the XAMPP file directories!

I've checked my C:\Windows\System32\drivers\etc\hosts, it has this code inside:

I have a FormGroup that has an element like this.

i have a project where i work with a bookshop. And when a user buys a book, i want to add a record in the SoldBooks table with info about the book and the user. But everything is fine with the add except when i want to add the User Id. Visual studio wont allow me to add an int "Cannot Implicitly convert type INT to models.User"

I have created windows forms application for a bookshop .it has login form and if a user forgot his password he can change password by clicking forgot password button. in the form "reset password " I have give regular expressions to validate for Username, new password ,confirm password textboxes .And also if user unwanted to reset his password it has a close button to Close the "Reset password" form. Then my question is when user click on close button it can't close the form and it display error message that I created for the regular expression for textboxes. how can I code to prevent this error message from regular expression and close that form anytime by clicking close button ?

this is the code in that form