PHP 日期转换成时间戳

/**
 * 日期转换成时间戳
 */
strtotime(date('Y-m-01 00:00:00'));

/**
 * 转换时间戳
 */
function changeTime($time, $miter = '/') {
    if ($time) {
        $timearr = explode($miter, $time);
        if (strpos($time, ':')) {
            $timearr2 = explode(" ", $time);
            $scd = explode(":", $timearr2[1]);
            $mtime = mktime($scd[0], $scd[1], $scd[2], $timearr[1], $timearr[2], $timearr[0]);
        } else {
            $mtime = mktime(null, null, null, $timearr[1], $timearr[2], $timearr[0]);
        }

        return $mtime;
    } else {
        return false;
    }
}

/**
 * 时间戳转时间
 *
 * @param unknown $time_stamp            
 */
function getTimeStampTurnTime($time_stamp)
{
    if ($time_stamp > 0) {
        $time = date('Y-m-d H:i:s', $time_stamp);
    } else {
        $time = "";
    }
    return $time;
}

function getTimeStampTurnTimeByYmd($time)
{
    $res = "";
    if ($time > 0) {
        $res = date("Y-m-d", $time);
    }
    return $res;
}

/**
 * 时间转时间戳
 *
 * @param unknown $time            
 */
function getTimeTurnTimeStamp($time)
{
    $time_stamp = strtotime($time);
    return $time_stamp;
}