<swustoj>?id=56 Hamming Distance

#include <stdio.h>
#include <string.h>
int main()
{
    int i,count;
    char str_1[105];
    char str_2[105];
    while(scanf("%s",str_1)&&str_1[0]!=‘X‘)
    {
        count=0;
        scanf("%s",str_2);
        for(i=0;i<strlen(str_1);i++)
        {
            if(str_1[i]!=str_2[i])
            {
                count++;
            }
        }
        printf("Hamming distance is %d.\n",count);
    }
    return 0;
}