58. 最后一个单词的长度

<?php
class Solution {
    /**
     * @param String $s
     * @return Integer
     */
    public function lengthOfLastWord($s) {
        if (!$s) return 0;
        $len = 0;
        $s = rtrim($s);
        for ($i = strlen($s) - 1; $i >= 0; $i--) {
            if ($s[$i] == ' ') break;
            $len++;
        }
        return $len;
    }
}
$s = "Hello World";
$cls = new Solution();
$r = $cls->lengthOfLastWord($s);
print_r($r);