int truncate(char s[], int n){
        if(strlen(s) > n){
                int removed = strlen(s) - n;
                s[n] = '\0';
                return removed;
        } else {
                return 0;
        }
}


Write a function named truncate() that takes a string s and a
    non-negative integer n. If s has more than n characters (not including the
    null terminator), the function should truncate s at n characters and
    return the number of characters that were removed. If s has n or
    fewer characters, s is unchanged and the function returns 0. For example,
    if s is the string "function" and n is 3, then truncate() changes s to
    the string "fun" and returns 5.