LeetCode: 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 sinNum;
        for(int i = 0;i < n; i++){
            sinNum = sinNum ^ A[i];
        }
        return sinNum;
    }
};