PHP Optional Function Arguments

Question

I'm a little stuck trying to create a function that takes a single, optional argument. Instead of this being a string I'd like it to be the result of a function (or even better, a DateTime object). Essentially - I want the user to either pass in a DateTime object, or for the function to resort to todays date if no arguments are supplied. Is this possible with PHP? By trying to create the new object in the function header as such

function myDateFunction($date = new DateTime()){
//My function goes here.
}

causes PHP to fall over.

Many thanks.

BlitZ · Accepted Answer · 2013-09-15 11:25:51Z

5

Yes. It is possible if you move $date instantiation to function body:

<?php
header('Content-Type: text/plain');

function myDateFunction(DateTime $date = null){
    if($date === null){
        $date = new DateTime();
    }

    return $date->format('d.m.Y H:i:s');
}

echo
    myDateFunction(),
    PHP_EOL,
    myDateFunction(DateTime::createFromFormat('d.m.Y', '11.11.2011'));
?>

Result:

15.09.2013 17:25:02
11.11.2011 17:25:02

From php.net:

Type hinting allowing NULL value

answered Sep 15, 2013 at 11:25

BlitZ

12.2k3 gold badges52 silver badges70 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

zerkms Over a year ago

"Yes. it is possible:" --- it's not. Don't confuse newbies

zerkms · Accepted Answer · 2013-09-15 11:23:58Z

5

The default value must be a constant expression, not (for example) a variable, a class member or a function call.

http://php.net/manual/en/functions.arguments.php#example-154

answered Sep 15, 2013 at 11:23

zerkms

256k73 gold badges447 silver badges551 bronze badges

Comments

Shankar Narayana Damodaran · Accepted Answer · 2013-09-15 11:27:12Z

2

You can do it this way:

function myDateFunction($date = null){
    if(is_null($date) || !($date instanceof DateTime)) {
        $date = new DateTime();
    }

    return $date;
}

var_dump(myDateFunction());

edited Sep 15, 2013 at 11:27

Shankar Narayana Damodaran

68.6k43 gold badges102 silver badges129 bronze badges

answered Sep 15, 2013 at 11:25

kelunik

6,9492 gold badges44 silver badges73 bronze badges

4 Comments

Oleg Belousov Over a year ago

Thank you sir for copying the solution that I've suggested with a minor modification(Who ever edited this).

kelunik Over a year ago

Haha, @OlegTikhonov, I didn't.

Oleg Belousov Over a year ago

Last time I've checked, PHP evaluates if(!($date instanceof DateTime)) the same as if($date !instanceof DateTime) but nevermind :)

kelunik Over a year ago

@OlegTikhonov: checked times: me ( answered 59 mins ago ), you ( answered 58 mins ago ) ;)

Jason OOO · Accepted Answer · 2013-09-15 11:26:10Z

1

You can use other option:

function myDateFunction($date = null){
 if(is_null($date)) $date = new DateTime();

}

answered Sep 15, 2013 at 11:26

Jason OOO

3,5622 gold badges28 silver badges32 bronze badges

Comments

Oleg Belousov · Accepted Answer · 2013-09-15 11:26:52Z

1

function myDateFunc($date = null){
   if(!isset($date) || $date !instanceof DateTime){
     $date = new DateTime()
   }
   /* YOur code here*/
}

answered Sep 15, 2013 at 11:26

Oleg Belousov

10.1k14 gold badges74 silver badges128 bronze badges

Comments

Bhumi Shah · Accepted Answer · 2013-09-15 11:24:53Z

0

for optional argument in your function, you can write code like

function myDateFunction($date = ''){
         //My function goes here.
         if($date==''){ $date = new DateTime()}
    }

hope it helps

answered Sep 15, 2013 at 11:24

Bhumi Shah

9,50210 gold badges69 silver badges110 bronze badges

1 Comment

zerkms Over a year ago

It's conventionally to use null instead of empty string to express the lack of data passed.

Collectives™ on Stack Overflow

PHP Optional Function Arguments

6 Answers 6

1 Comment

Comments

4 Comments

Comments

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

6 Answers 6

1 Comment

Comments

4 Comments

Comments

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related