如果语句使用日期和 strtotime 返回错误结果

Question

I'm trying to use an if statement to say "If today is between two dates, do this..." etc.

It's not working, and I'm at a total loss because as far as I can see - it SHOULD work!

if (date('d/m/y', strtotime('now')) >= date('d/m/y', strtotime('1 January 2021')) && date('d/m/y', strtotime('now')) <= date('d/m/y', strtotime('31 January 2021'))):
    echo 'true';
else:
    echo 'false';
endif;

Today is 3rd of December 2020 - so why is it telling me this statement is true?

PS. It does work if I change it to either, or both > 30th December 2020 and < 1st February 2021 - but I'm wary to do this in case it's just a glitch and I've made an obvious coding mistake.

Answer 1

First of all. It's not December 3rd now it's the first of December.

The problem you have is because you are trying to compare strings.
Date() returns strings and as far as I know no programming language can properly (whatever properly means in this context) compare > or < with strings. It's either === or.==.

So use the Unix times in the comparison since that is numeric and much easier for the computer to understand.

$now = strtotime('now');
$start = strtotime('1 January 2021');
$end = strtotime('31 January 2021');

if ($now >= $start && $now <= $end):
    echo 'true';
else:
    echo 'false';
endif;

https://3v4l.org/KAvQ2

Answer 2

date('d/m/y') gives you a string like 30/11/20 . Comparing dates in this format really means you're comparing strings, which only works if the dates are in YYYYMMDD (or YYYY-MM-DD) format.

It's much easier to just use strtotime() to turn the English-like date into a Unix timestamp (just a big integer) and compare them directly:

if ( 
    strtotime('now') >= strtotime('1 January 2021')
        &&
    strtotime('now') <= strtotime('31 January 2021')
) {
    echo 'true';
} else {
    echo 'false';
}

Answer 3

You really should be using DateTime class for all your date-related calculations. Don't use the old strtotime() or date() unless you really know what you're doing.

With DateTime class it's really simple:

<?php

$start = new DateTime('1 January 2021');
$end = new DateTime('31 January 2021');
$today = new DateTime();
if($today >= $start && $today <= $end){
    echo 'In between';
} else {
    echo 'outside or range';
}

Demo

Answer 4

Replace your code with following.

if (strtotime(date('d/m/y', strtotime('now'))) >= strtotime(date('d/m/y', strtotime('1 January 2021'))) && strtotime(date('d/m/y', strtotime('now'))) <= strtotime(date('d/m/y', strtotime('31 January 2021')))):
    echo 'true';
else:
    echo 'false';
endif;