leetcode 题解: Length of Last Word

leetcode：

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.

说明：给定一个字符串，返回最后一个word的长度

       1）字符串后面可以有空格，所以要去尾部空格

       2）可能不含word,所以要判断字符串是否为空、或者是否只含有空格

class Solution {
public:
    int lengthOfLastWord(const char *s) {
        int len=strlen(s);
        while(s[len-1]==' ') len--; //去尾部空格
        if(len<0) return 0; //去空格后是否为空字符串
        int i=0;
        for(;s[len-1]&&s[len-1]!=' ';i++,len--); //求最后word长度
        return i;
    }
};