php 检查日期是否合法日期

<?php
function check_date($date) { //检查日期是否合法日期 
$dateArr = explode("-", $date); 
    if (is_numeric($dateArr[0]) && is_numeric($dateArr[1]) && is_numeric($dateArr[2])) { //开源OSPhP.COM.CN 
        return checkdate($dateArr[1],$dateArr[2],$dateArr[0]); 
    } 
    return false; 
} 
function check_time($time) {  //检查时间是否合法时间
//OSPHP.COM.Cn开源
$timeArr = explode(":", $time); 
    if (is_numeric($timeArr[0]) && is_numeric($timeArr[1]) && is_numeric($timeArr[2])) {
//开源代码OSPHP.COM.Cn
        if (($timeArr[0] >= 0 && $timeArr[0] <= 23) && ($timeArr[1] >= 0 && $timeArr[1] <= 59) && ($timeArr[2] >= 0 && $timeArr[2] <= 59))
//PHP开源代码
            return true; 
        else
            return false; 
    } 
    return false; 
} 
function DateDiff($date1, $date2, $unit = "") { //时间比较函数，返回两个日期相差几秒、几分钟、几小时或几天 
switch ($unit) { 
        case 's': 
$dividend = 1; 
            break; 
        case 'i': 
$dividend = 60;
//oSPHP.COM.CN
            break; 
        case 'h': 
$dividend = 3600; 
            break; 
        case 'd': 
$dividend = 86400; 
            break; 
        default: 
$dividend = 86400; 
    } 
$time1 = strtotime($date1); 
$time2 = strtotime($date2); 
    if ($time1 && $time2) //OSPHP.com.CN 
        return (float)($time1 - $time2) / $dividend; 
    return false; 
} 
?>
//该片段来自于http://outofmemory.cn