Solved: Add months to date | Experts Exchange

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tonelm54

Add months to date

I have a simple issue, where I need to add a number of months to a date, the input date format I cannot change, it will always be dd/mm/YYYY (eg 27/04/2021) as its coming from a html5 input control of date.

So, I generated my code which I thought would work according to several examples Ive found on the web:-

<?php
$inputDate = "27/04/2021";
$noMonths2Add = 3;
$effectiveDate = strtotime("+".$noMonths2Add." months",strtotime($inputDate));
echo json_encode(array("newDate"=>date('Y-m-d',$effectiveDate)));

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And it spits out {"newDate":"1970-01-31"} - Which is NOT correct

Any ideas of what Ive done wrong?

Sorry, I could spend ages on this trying to figure out, but not had time to play with this, so probably a really simple issue :-(

Thank you in advance though

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ste5an🇩🇪

Your strtotime() usage in line 4 is pretty creative. The add part belongs to the end.

$effectiveDate = strtotime($inputDate."+".$noMonths2Add." months");

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But why not using DateTime instead?

tonelm54

ASKER

I have looked at using DateTime in OOP, but it seems a bit too complicated for what I thought was a simple solution :-S

I tried replacing your line in my code:-

<?php

$inputDate = "27/04/2021";
$noMonths2Add =3;
$effectiveDate = strtotime($inputDate."+".$noMonths2Add." months");

echo json_encode(array("newDate"=>date('Y-m-d',$effectiveDate)));

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Which still gives the wrong date :-( :-

{"newDate":"1969-12-31"}

ASKER CERTIFIED SOLUTION

Ryan Chong🇸🇬

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ste5an🇩🇪

The 1970 in the first case and now the 1969, means that some parsing problem or error happens and it fails back to epoch.

So look at the output of your format and the result of the date calculus.

<?php
$inputDate = "27/04/2021";
$noMonths2Add = 3;
$effectiveDate = strtotime($inputDate."+".$noMonths2Add." months");
$formattedDate = date('Y-m-d',$effectiveDate);
echo $effectiveDate." --- ".$formattedDate." --- ".json_encode(array("newDate"=>$formattedDate));

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tonelm54

ASKER

When I try with the code:-

$inputDate = "27/04/2021";
$noMonths2Add = 3;

$effectiveDate = DateTime::createFromFormat("d/m/Y", $inputDate)->modify("+".$noMonths2Add." months")->format("Y-m-d"

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I get Fatal error: Uncaught Error: Call to a member function modify() on bool

Seems to be when I run:-

DateTime::createFromFormat("d/m/Y", $inputDate);

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It returns false :-S

Ryan Chong🇸🇬

make sure you written a valid php code.

this worked for me:

<?php

$inputDate = "27/04/2021";
$noMonths2Add = 3;

$effectiveDate = DateTime::createFromFormat("d/m/Y", $inputDate)->modify("+".$noMonths2Add." months")->format("Y-m-d");

echo $effectiveDate;

?>

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