str_翻转字符串

1. 给一个句子，翻转每个单词，单词内部不翻转

$str = "dog loves pig";
$ret = turnSentence($str);
var_dump($ret);

function turnSentence($str1)
{
    $str2 = turnWord($str1);
    $str2_arr = explode(' ', $str2);
    foreach ($str2_arr as $key => &$value) {
        $value = turnWord($value);
    }
    unset($value);
    return implode(' ', $str2_arr);
}

function turnWord($str) // 用php处理字符串函数strrev更优
{
    $length = strlen($str);
    $ret = '';
    for ($i = $length - 1; $i >= 0; $i--) {
        $ret .= $str{$i};
    }
    return $ret;
}

输出结果： pig loves dog