PHP - date function to go back in time week by week for a year-CodePudding

I have the following code:

$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"));
}

The original two dates it gives me are correct but when I try to jump back a week I get an error saying A non well formed numeric value encountered.

I am not sure why this is happening or how I should fix this, any suggestions would be great.

CodePudding user response：

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

use this way to get currect output

date("Y-m-d",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)));
    }
?>

CodePudding user response：

The function strotime expects a date string in the first argument and in the second argument a timestamp as base time.

You can change your code to use the DateTime object and manipulate the date on this.

<?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");
}