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php – Why can't I call property_exists on stdClass?

Posted by: admin July 12, 2020 Leave a comment

Questions:

Here is my code:

<?php

$madeUpObject = new \stdClass();
$madeUpObject->madeUpProperty = "abc";

echo $madeUpObject->madeUpProperty;
echo "<br />";

if (property_exists('stdClass', 'madeUpProperty')) {
    echo "exists";
} else {
    echo "does not exist";
}
?>

And the output is:

abc
does not exist

So why does this not work?

How to&Answers:

Try:

if( property_exists($madeUpObject, 'madeUpProperty')) {

Specifying the class name (instead of the object like I have done) means in the stdClass definition, you’d need the property to be defined.

You can see from this demo that it prints:

abc
exists 

Answer:

Because stdClass does not have any properties. You need to pass in $madeUpObject:

property_exists($madeUpObject, 'madeUpProperty');

The function’s prototype is as follows:

bool property_exists ( mixed $class, string $property )

The $class parameter must be the “class name or an object of the class“. The $property must be the name of the property.

Answer:

Unless you’re concerned about NULL values, you can keep it simple with isset.