PHP function return value, how to check

Question

First a simple example:

function doReturnSomething()
{
    // some logic
    if ($resultFromLogic) {
        return Default_Model_Something;
    }

    return false;
}

As you can see, this functions returns a model or false. Now, let's call this function from some place else:

$something = doReturnSomething();

No, I want to put a if-statement to check the variable $something. Let's say:

if (false !== $something) {}

or

if ($something instanceof Default_Model_Something) {}

or

...

Is there a "best practice" for this situation to do? Check for false or use instance of. And are there any consequences for that particular way?

Thank is advance!

Not directly to the question, but I suggest to return null instead of a bollean, because a) null is the equivalent of "nothing", which seems to fit here quite well, and b) there may be situations, where the return value should be a boolean and then you cannot distinguish between "nothing" false and "value" false — KingCrunch
– KingCrunch, Commented Jan 16, 2012 at 12:37

KingCrunch · Accepted Answer · 2012-01-16 12:37:29Z

1

Depending on what it is returning, you could just do this:

if(doReturnSomething()) {}

It will return true when an object is returned (Default_Model_Something) and return false when false is returned or a null-value. Just don't use this way when working with numbers because "0" will evaluate to false.

edited Jan 16, 2012 at 12:37

KingCrunch

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answered Jan 16, 2012 at 12:32

JNDPNT

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4 Comments

KingCrunch Over a year ago

This way works well with numbers, as long as (you mentioned it) 0 is not a valid value. For example IDs usually starts with 1

Vincent van Dijk Over a year ago

That's true. When using instanceof, we can be sure that particular methods / properties are available from the class Default_Model_Something. Are there any disadvantages when using instanceof? If "false !==" a more generic way of typing?

Uday Sawant Over a year ago

Hey, sorry if i m getting it wrong, but what if doReturnSomething() returns valid model and i have to access it inside if braces. it would be better to use it like $something = doReturnSomething(); and then if($something){}

JNDPNT Over a year ago

Yes of course... when you need it on multiple locations you should store it in a variable and check the variable instead. @VincentvanDijk: instanceof also works, but it has limitations in flexibility etc. When you have to depend on certain functions however, I guess it would be best to create some sort of an interface so you can just plugin new classes.

hakre · Accepted Answer · 2012-07-18 18:39:33Z

1

I think that from PHP 5.4 on there is a special notice error for threating a function return in logical statements.

Good pratice is to save result of a function to variable and then use it in any logical statement.

edited Jul 18, 2012 at 18:39

hakre

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answered Jul 17, 2012 at 15:13

Bartosz Rychlicki

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1 Comment

hakre Over a year ago

I don't think there is such a notice. You can try here online: codepad.viper-7.com - The other part in your answer sounds good IMHO, but maybe you could tell why?

Alexander Farber · Accepted Answer · 2016-12-01 10:23:47Z

-1

<?php function my($a, $b ,$c){

    $total = $a + $b - $c;      return $total;       }

$myNumber = 0;

echo "Before the function, myNumber = ". $myNumber ."<br />";

$myNumber = my(3, 4, 1); // Store the result of mySum in $myNumber

echo "After the function, myNumber = " . $myNumber ."<br />";

?>

edited Dec 1, 2016 at 10:23

Alexander Farber

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answered Dec 1, 2016 at 10:19

user7235633

1

1 Comment

Pang Over a year ago

What does this have to do with the question asked?

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