PHP, why does php recognize May 1st is less than 28th April?

Question

I am trying to compare previous date with today which is May 1st, but turns out that previous date is higher than today. I wonder why is this happened and how to solve it?

PHP

$api_date = '2021-04-28T06:30:00Z';
$previous_date = date('d-m-Y , H:i', strtotime($api_date));
$today_date = date('d-m-Y , H:i');

if($previous_date <= $today_date)
    print_r('true');
else{
    print_r('false'); //will return this, why?
}

You print false in every case. How can you knows that return the second option? — Stefino76, May 01 '21 at 06:52
You are comparing strings and as the day is first you are comparing `01` and `28`. — Nigel Ren, May 01 '21 at 07:02
Check https://stackoverflow.com/questions/2113940/compare-given-date-with-today — Nigel Ren, May 01 '21 at 07:09
@NigelRen seems like not much different, most of the are comparing with strings — LearnProgramming, May 01 '21 at 07:24
They may be comparing with strings, but they have the year at the start and not the day. — Nigel Ren, May 01 '21 at 07:25
`Why?` Because string comparisons are done character by character, so you need to start with the largest item (I.e. the 4-digit year, so the millennium comes first and the day comes last). It has no idea the string is supposed to be a date. The DateTime class should be used if you want something more robust. `How?`...just like the examples you were linked to. — ADyson, May 01 '21 at 07:42

score 1 · Accepted Answer · answered May 01 '21 at 08:24

solution: just change the date format to year-month-day, thx to @Nigel Ren

$api_date = '2021-04-28T06:30:00Z';
$previous_date = date('Y-m-d , H:i', strtotime($api_date));
$today_date = date('Y-m-d , H:i');

if($previous_date <= $today_date)
    print_r('true'); //will return this
else{
    print_r('false');
}

PHP, why does php recognize May 1st is less than 28th April?

1 Answers1