[原创]实现从当前月向下推N个月的函数

<?

/*

*  作者:心灯

*  功能:实现从指定时间向下推N个月的函数

*  month($ymd,$len) $ymd时间，$len推出几个月

*  $ymd='2005-01-01';

*/

function month ( $ymd = '' , $len = '12' ){

     $month   = array();

     $lang    = $lang . "<meta http-equiv=/"Content-Type/" content=/"text/html; charset=gb2312/">" ;

    if( $ymd ){ //判断时间格式是否正确

         if(! ereg ( "([0-9]{4})-([0-9]{1,2})-([0-9]{1,2})" , $ymd )){            

            echo "<script>alert('函数参数中的日期格式不对');history.back()</script>" ;

            exit;

        }

    }

    if( $len ){

        if(! ereg ( "[0-9]+" , $len )){            

            echo $lang . "<script>alert('函数中的时间长度中含有非法字段');history.back()</script>" ;

            exit;

        }

    }

    for( $i = 0 ; $i < $len ; $i ++){

        if( $i == 0 ){

             $mktime = $ymd ? strtotime ( $ymd ): time ();

        }

         $month [] = date ( "Y-m" , $mktime ); //可以根据需要来设计置你要的格式

         $day = date ( "t" , $mktime );

        if( $i == 0 )

             $reday = date ( "d" , $mktime );

        else

             $reday = $day ;

         $t1    = $mktime ;

         $mktime = date ( "Y-m-d" , mktime ( date ( "H" , $t1 ), date ( "i" , $t1 ), date ( "s" , $t1 ), date ( "m" , $t1 ), date ( "d" , $t1 )- $reday , date ( "Y" , $t1 )));

         $mktime = strtotime ( $mktime );        

    }

    return $month ;

}

$month = month ();

foreach( $month as $key => $v ){

    echo $v . "<br>" ;

}

?>


效果如下：
2005-01
2004-12
2004-11
2004-10
2004-09
2004-08
2004-07
2004-06
2004-05
2004-04
2004-03
2004-02