PHP - 日期 function 到 go

Question

我有以下代碼：

$last_week_start = date("Y-m-d",strtotime("monday last week"));
$last_week_end = date("Y-m-d",strtotime("sunday last week"));

for($i=52;$i>0;$i--){
    //do stuff with the dates for this week

    $last_week_start = date("Y-m-d",strtotime($last_week_start,"-7 days"));
    $last_week_end = date("Y-m-d",strtotime($last_week_end,"-7 days"));
}

它給我的最初兩個日期是正確的，但是當我嘗試跳回一周時，我收到一條錯誤消息，指出A non well formed numeric value encountered 。

我不確定為什么會這樣或者我應該如何解決這個問題，任何建議都會很好。

Answer 1

function strotime在第一個參數中需要一個日期字符串，在第二個參數中需要一個時間戳作為基准時間。

您可以更改代碼以使用DateTime object 並在此操作日期。

<?php
$last_week_start = new \DateTime("monday last week");
$last_week_end = new \DateTime("sunday last week");

for($i=52;$i>0;$i--){
    //do stuff with the dates for this week

    $last_week_start->modify("-7 days");
    $last_week_end->modify("-7 days");
    $last_week_start_formatted = $last_week_start->format("Y-m-d");
    $last_week_end_formatted = $last_week_end->format("Y-m-d");
}

Answer 2

strtotime(time, now); Required. Specifies a date/time string

使用這種方式獲得正確的 output

date("Ymd",strtotime("-7 days",strtotime($last_week_start)))

<?PHP
    $last_week_start = date("Y-m-d",strtotime("monday last week"));
    $last_week_end = date("Y-m-d",strtotime("sunday last week"));
    echo $last_week_start." ".$last_week_end;
    for($i=52;$i>0;$i--){
        //do stuff with the dates for this week
    
        $last_week_start = date("Y-m-d",strtotime("-7 days",strtotime($last_week_start)));
        $last_week_end = date("Y-m-d",strtotime("-7 days", strtotime($last_week_end)));
    }
?>