CODEWITHSUNDEEP
phpphp-7.1null-coalescing-operator
Houssem ZITOUN
Houssem ZITOUN

Reputation: 732

Php Null coalescing operator

I am trying to understand how the null coalescing operator does really work. So, I tested many examples after reading the documentation in php.net and some posts on stackoverflow.

However, I can't understand this code:

<?php 
$x = false ?? 'stackoverflow';
var_dump($x); // bool(false)

since it's equivalent to (from php.net#null-coalescing)

isset(false) ? false : 'stackoverflow';

and since isset(false) generates a fatal error.

Could, please, someone explain to me?

Upvotes: 1

Views: 2175

Answers (1)

Kawaljeet Singh
Kawaljeet Singh

Reputation: 357

Null coalescing operator returns its first operand if it exists and is not NULL;

Otherwise it returns its second operand.

In your case first operand is false so it is assigned to the variable. For e.g; if you initialize null to first operand then it will assign second operands value as shown. 

 $a = null;
 $x = $a ?? 'abc';
 var_dump($x);

Result :
string(3) "abc"

Upvotes: 2

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