php获取当前日期-7天

// 将目前的时间戳值放入一数组内
$strdate = '2014-02-03';
$desDate = strtotime($strdate);
//var_dump($desDate);

$timestamp = time();
//echo " originalDate:".date('Y-m-d',time())." ";
echo " originalDate:".date('Y-m-d',$desDate)." ";

//$date_time_array = getdate($timestamp);
$date_time_array = getdate($desDate);
$hours = $date_time_array["hours"];
$minutes = $date_time_array["minutes"];
$seconds = $date_time_array["seconds"];
$month = $date_time_array["mon"];
$day = $date_time_array["mday"];
$year = $date_time_array["year"];
// 用mktime()函数重新产生Unix时间戳值减7天
$timestamp = mktime($hours, $minutes, $seconds, $month, $day-7, $year);
echo " addSevenDate:".date('Y-m-d',$timestamp)." ";

echo " ------ ";
$yestertime = date ( 'Y-m-d', strtotime("-7 day",$desDate) );
echo "maethod2:".$yestertime;