Thread: Sort array seg fault

Although I could use std::sort() I decided to attempt to sort a string array using bubble sort.

It compiles but I get a seg-fault noted below at a certain point. The exact same algorithm worked fine on an integer array, but it doesnt seem to like the strings,
or is there a more convient sorting method for strings other than cheating with std::sort()?

Code:

#include <iostream>
#include <string>

// function prototype
void sortNames ( std::string[], const int );

// main function - driver /////////////////////////////////////////////////////
//
int main ( void ) {
	const int ARRAY_SIZE = 20;

	std::string names[ ARRAY_SIZE ] = { "" };

	std::cout << "Enter 20 names: ";

	for ( int i = 0; i < ARRAY_SIZE; i++ ) {
		std::getline ( std::cin, names[ i ] );
	}

	sortNames ( names, ARRAY_SIZE );

	std::cout << "\n\nIn Order:\n\n";

	for ( int i = 0; i < ARRAY_SIZE; i++ ) {
		std::cout << names[ i ] << std::endl;
	}

	std::cin.get();

	return 0;
}

// function to print the names out alphabetically
void sortNames ( std::string nm[], const int SIZE ) {

	for ( int pass = 1; pass < SIZE +1; pass++ ) {
		for ( int i = 1; i < SIZE +1; i++ ) {
			if ( nm[ i ] > nm[ i + 1 ] ) {
				std::string temp = nm[ i ];
				nm[ i ] = nm[ i + 1 ]; // SEG FAULTS
				nm[ i + 1 ] = temp;
			}
		}
	}
}

You are indexing past the nm[] array on SIZE+1.

If you are doing any sort of array loop, and then you have an array i+1, then you'll eventually hit--in your case --- 21, which will give you a segmentation fault, because you had an access violation. You should check if it's the last i, before you do an i+1, because you are calling something that may not even exist.

Thanks so much guys.

Merrry Xmas