Length of Last Word

Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string.

If the last word does not exist, return 0.

Note: A word is defined as a character sequence consists of non-space characters only.

For example, 
Given s = "Hello World",
return 5.

    int lengthOfLastWord(const char *s) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        int l = strlen(s);
        if(l == 0)
            return 0;
        int result = 0;
        while(s[l-1] == ' ' && l > 0)
            l--;
        while(s[l-1] != ' ' && l > 0){
            l--;
            result++;
        }
        return result;
    }