如何使用PHP获取指定日期所在月的开始日期与结束日期

复制代码 代码如下:
  
    private function getMonthRange( $date, $returnFirstDay = true ) {
        $timestamp = strtotime( $date );
        if ( $returnFirstDay ) {
            $monthFirstDay = date( 'Y-m-1 00:00:00', $timestamp );
            return $monthFirstDay;
        } else {
            $mdays = date( 't', $timestamp );
            $monthLastDay = date( 'Y-m-' . $mdays . ' 23:59:59', $timestamp );
            return $monthLastDay;
        }
    }