cs106b | CS 106B : Programming Abstractions | Interpreter library

I am working with an XML type database in PHP. Using SimpleXML I'm working with the documentation. But when collecting a value, it remains in the first node.

Here XML-DataBase

I'm trying to solve a problem given in the free online CS106B course from Stanford. The text of the problem shown below. I have written a function, but I'm not sure if the logic is right (not one of those programs when you know you have the right answer). Please see problem and my code below. I'd appreciate any feedback/suggestions.

PROBLEM: Consider a 1000-voter election with a single percentage point spread between two candidates, i.e. 50.5% vote for one candidate, 49.5% for the other. The voting machine makes an error 8% of the time and records a vote for the opposite candidate than intended. Is this error rate high enough to invalidate the results of the election? With a little knowledge of statistics, it is not hard to calculate the exact probability of an invalid outcome, but it is even easier to simulate this process. Generate a sequence of 505 votes for candidate A and 495 for candidate B where each vote has a 8% chance of being inverted when recorded. Do the vote totals result in B defeating A, despite the original intentions of the voters? This outcome represents one trial in the simulation. If you repeat this trial many times and keep track of the results, the ratio:

(number of trials in which election result was invalid)/(total number of trials)

provides an estimate of the percentage chance of an invalid election result.

Write a program that prompts the user to enter the voting simulation parameters, then performs 500 simulation trials and reports the ratio calculated above. A sample run of the program is shown below:

Enter number of voters: 10000 Enter percentage spread between candidates: .005
Enter voting error percentage: .15 Chance of an invalid election result after 500 trials = 13.4%

Your program should take care to verify the user's chosen simulation parameters are within range (percentages must be 0 to 1.0 and number of voters should be positive) and if necessary, re-prompt for valid input. Note that because of the randomness in the simulation, it is expected that the results will vary from run to run.

CODE (P.S. I used Stanford CPP libraries):

I want to do the CS106b/CS106x course of Stanford but have problems running a C++ sample project in Qt successfully. So far it is possible for me to build the project but when I try to run it, the following error message is always shown: