shift strings(use 3 reverse)

shift_str.c

void reverse(char* s, int start, int end)
{
    char t;
    while(start < end)
    {
        t = s[start];
        s[start++] = s[end];
        s[end--] = t;
    }
//    printf("%s\n", s);
}

void shift(char* s, int n, int length)
{
    n = n % length;
//    printf("--%s %d\n", s, length);
    reverse(s, 0, n - 1);
    reverse(s, n, length - 1);
    reverse(s, 0, length - 1);
}