Learn How To Use Double Question Mark Operator In PHP

Posted By Bajarangi soft , Posted On 16-09-2020

Double question mark (??) operator mean in PHP will evaluates from left to right

List of Double question mark (??) operator mean in PHP

In PHP 7 has added a new operator double question mark (??) operator.
double question mark (??) operator known as Null Coalescing Operator.
It returns its first operand if it exists and is not NULL otherwise, it returns its second operand.
It evaluates from left to right.
Null Coalescing operator also can be used in a chain format.

Example(1)

<?php
     echo $x ?? 6 ??  32; //$a is not set
?>

output : 6

Example(2)

<?php

$b = 54;
echo $a ?? $b ?? 5;//$a is not set
?>

output : 54

Example(3)

<?
$foo = $bar ?? 'something';
$foo = isset($bar) ? $bar : 'something';

echo $foo;
?>

output : something

Complete Code to Double question mark (??) operator :

<!DOCTYPE html>
<html>
<head>
    <title>double question mark (??) operator mean in PHP</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css">
</head>
<body>
<div class="container">
    <br>
    <br>
    <div class="text-center">
        <h1>Double question mark (??) operator mean in PHP</h1>
    </div>
    <br>
    <br>
    <div class="well">

        <?php
        //$a is not set
        echo $x ?? 6 ??  32;
        
        echo "<br>";
        echo "<br>";
        //$a is not set
        $b = 54;
        echo $a ?? $b ?? 5;

        echo "<br>";
        echo "<br>";

        $foo = $bar ?? 'something';
        $foo = isset($bar) ? $bar : 'something';

        echo $foo;
        ?>
    </div>
    <br>
</div>
</body>
</html>

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