php计算给定日期所在周的开始日期和结束日期

<?php
/**
 * 取得给定日期所在周的开始日期和结束日期
 * @param string $gdate 日期，默认为当天，格式：YYYY-MM-DD
 * @param int $weekStart 一周以星期一还是星期天开始，0为星期天，1为星期一
 * @return array 数组array( "开始日期 ",  "结束日期");
 */
function getAWeekTimeSlot($gdate = &#39;&#39;, $weekStart = 0) {
 if (! $gdate){
 $gdate = date ( "Y-m-d" );
 }
 $w = date ( "w", strtotime ( $gdate ) ); //取得一周的第几天,星期天开始0-6
 $dn = $w ? $w - $weekStart : 6; //要减去的天数
 $st = date ( "Y-m-d", strtotime ( "$gdate  - " . $dn . "  days " ) );
 $en = date ( "Y-m-d", strtotime ( "$st  +6  days " ) );
 return array ($st, $en ); //返回开始和结束日期
}
$timeSlot=getAWeekTimeSlot(&#39;2017-01-24&#39;,1);
echo "Week Start:{$timeSlot[0]}--->Week End: {$timeSlot[1]} ";
?>

Week Start:2017-01-23--->Week End: 2017-01-29