. Programming: a set of data in a number appears only once. All other numbers are in pairs. Look for this number. (Using bit operation)

 

#include<stdio.h>  
int main()
{
    int arr[] = { 1, 5, 5, 1, 7, 6, 7, 8, 8,9,9};
    int i = 0;
    int len = sizeof(arr) / sizeof(arr[0]);


    for (i = 1; i < len; i++)
    {
        arr[0] = arr[0] ^ arr[i];//^异或运算符，相异为1想用为0.
    }
    printf("the single number is:%d", arr[0]);
    return 0;
}