Single Number

Given an array of integers, every element appears twice except for one. Find that single one.

Note:
Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

class Solution {

public:

    int singleNumber(int A[], int n) {

        int data=0;

        for(int i=0;i<n;i++)

            data=data^A[i];

        return data;

    }

};