What is the Purpose of PHP\'s ?: Operator?

Understanding the PHP 5.3 ?: Operator

Introduced in PHP 5.3, the ?: operator offers a concise syntax for conditional expressions. It essentially simplifies the previously available conditional operator:

<code class="php">expr ? val_if_true : val_if_false</code>

Now, with the ?: operator, you can omit the middle expression:

<code class="php">expr ?: val_if_false</code>

This is equivalent to:

<code class="php">expr ? expr : val_if_false</code>

For example, the following code demonstrates the use of the ?: operator:

<code class="php">&lt;?php
require __DIR__.'/c.php';
if (!is_callable($c = @$_GET['c'] ?: function() { echo 'Woah!'; }))
    throw new Exception('Error');
$c();
?&gt;</code>

Decoding Anonymous Functions

PHP also introduced the concept of anonymous functions with PHP 5.3. These functions, sometimes referred to as lambda functions, can be defined on-the-fly and passed as arguments to other functions.

Anonymous functions exist as an object of the Closure class and can be assigned to variables or passed directly as arguments. These functions provide a convenient way to write short, inline code blocks without requiring a separate function definition.

For instance, in the example provided:

<code class="php">function() { echo 'Woah!'; }</code>

is an anonymous function that outputs "Woah!" when called.

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