asked on

php date add

One of those days when EVERYTHING goes wrong.

What is wrong with this:

<?php
$today = date('Y-m-d');
// 30 days out
$exp = date_add($today, date_interval_create_from_date_string('30 days'));
echo $exp;
?>

Open in new window

I get Warning: date_add() expects parameter 1 to be DateTime, string given in /home/backflow/public_html/date_add_test.php on line 4

What does it want, that IS date / time?

Donna

Yes, you need to read the manual. date_add() Adds an amount of days, months, years, hours, minutes and seconds to a DateTime object, and returns another DateTime object. So param1, which is $today, should be a DateTime object, but it's a String. (and it's returned as a String on line 2)

http://php.net/manual/en/function.date-add.php
http://php.net/manual/en/datetime.add.php

Donna

If you want to create a DateTIme object from the date (is that even what you want?) you can try this:

http://php.net/manual/en/datetime.construct.php

DateTime date_create ([ string $time = "now" [, DateTimeZone $timezone = NULL ]] )

> (Returns new DateTime object.)

What is it you are trying to do?

Brian Tao

The date() function returns a date/time formatted string. The date_add() function requires the first parameter to be a DateTime object rather than a date/time formatted string.
Use the following instead:

// procedural style
$today = date_create();
// or OO style
$today = new DateTime();

Open in new window

Richard Korts

ASKER

seems to me the "old fashioned" way is much easier.

1. Use mktime for time now.
2. multiply # of days by 86400.
3. add those seconds to time now
4. convert to date.

SOLUTION

Donna

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

ASKER CERTIFIED SOLUTION

Scott Fell

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

SOLUTION

Ray Paseur

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

Richard Korts

ASKER

I used this:

$tnow = mktime (date("H"), date("i"), date("s"), date("n"), date("j"), date("Y"));
// 30 days out
$addsecs = 30 * 86400;
$t30 = $tnow + $addsecs;

Works perfect.

Seems like translating 30 days to seconds should work regardless of DST or Feb, 28 or 29 days, etc.

I used this in 2006 on a site, it still works.

Ray Paseur

I used this in 2006 on a site, it still works.

You've been fortunate! It's only going to be the wrong calculation when the script runs at a time that sends its reach across the DST change. To my mind, that is one of the things that I know can go wrong, and I don't want a call from an irate client at 2:00am when the time resets. For me, it's just easier to "do it right."