What are PHP magic constants? PHP मैजिक कॉन्स्टेंट्स क्या हैं?

Short Answer

Anonymous functions (also known as Closures) are functions that have no name. They are most commonly used as callback parameters for functions like array_map, or assigned directly to variables.

Detailed Explanation & Code Example

Unlike regular functions defined globally with the function keyword and a name, anonymous functions can be created on the fly and passed around like data.

// Assigning an anonymous function to a variable
$greet = function($name) {
    return "Hello, $name";
};

echo $greet("World"); // Output: Hello, World

The use Keyword (Closures)

A massive advantage of anonymous functions in PHP is their ability to inherit variables from the parent scope using the use keyword. This makes them incredibly powerful for data filtering and manipulation.

$multiplier = 3;
$numbers = [1, 2, 3];

// Using a closure to access $multiplier from the parent scope
$multiplied = array_map(function($num) use ($multiplier) {
    return $num * $multiplier;
}, $numbers);

// $multiplied is now [3, 6, 9]