string Subscript out of range

[Hailhaven]

Hi there, I am new to coding and have run into a problem where I see the above error message and my programme is unable to run.
The code where I recieve this error is my attempt at http://projecteuler.net/problem=4

I am unsure what I am doing wrong, so if you could possibly have a look through my code and see if there are any errors I have made and suggest a working method of getting around these problems, it would be greatly appreciated.

Thanks

// EulerProblemFOUR.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
#include <string>
#include <sstream>
using namespace std;

string product;
int productResult;
short firstNumber = 999;
short secondNumber = 999;
const short maxPalindromes = 3;
	int highestPalindromes[maxPalindromes];
short currentPalindrome=0;
int Answer;

void checkPalindrome() {
	if (product[0] == product[5] && product[1] == product[4] && product[2] == product[3]) {
		cout << product << " is a Palindrome number!" << endl;
		highestPalindromes[currentPalindrome] = productResult;
		currentPalindrome++;
	}
	else if (firstNumber - secondNumber >= 10) {
		firstNumber -= 1;
		secondNumber = firstNumber;
	}
	else {
		secondNumber-= 1;
	}
}

void answerPalindrome() {
	if (highestPalindromes[0] >= highestPalindromes [1] && highestPalindromes[0] >= highestPalindromes[2])
	{
cout << "the highest Palindrome is " << highestPalindromes[0];
	}
	else if (highestPalindromes[1] >= highestPalindromes [0] && highestPalindromes[1] >= highestPalindromes[2])
	{
		cout << "the highest Palindrome is " << highestPalindromes[1];
	}
	else 
	{
		cout << "the highest Palindrome is " << highestPalindromes[2];
	}
}

int main() {
	do {
		productResult = firstNumber * secondNumber;
	product = productResult;
	checkPalindrome();
	}
	while (currentPalindrome <= 2);
	answerPalindrome();
	return 0;
}

[AbstractionAnon]

For one thing, at line 52 you're trying to assign an integer to a string.
That's not going to work.

[Hailhaven]

Is there a way I could retrieve a certain number from an integer, e.g. the second number of my integer 'productResult'?

[3qX21hU5]

Is there a way I could retrieve a certain number from an integer, e.g. the second number of my integer 'productResult'?

You can use stringstreams to convert the integer to a string and then grab the second "digit" from productResult and then convert it to a integer again if you need to do more calculation on it.

Or better yet just use simple mathmatics to grab a second digit from your number.


Also I would highly suggest you get away from declaring all your variables globally since that will cause you major problems in the future and is considered a very bad practice. You also should learn about function parameters and passing your variables into your functions as arguments instead of having them globally declared.

[Hailhaven]

Thanks very much!

With stringstreams, I was able to get my programme to work correctly.
I will look into your suggestion for avoiding global variables... thanks!!