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Explain the Dynamic Function Calls in PHP ?

In PHP, dynamic function calls allow developers to call a function whose name is determined at runtime instead of being hardcoded. It helps create more flexible and generic code.

There are mainly two ways to achieve dynamic function calls in PHP:

1. Using Variable Functions

PHP allows you to use strings containing the function name as variables to call functions dynamically.

  • call_user_func()
  • call_user_func_array()

The call_user_func() function takes the function name as the first argument and optional arguments to be passed to the function as subsequent arguments.


function greet($name) {
    echo "Hello, $name!";

$functionName = 'greet';
call_user_func($functionName, 'John'); // Output: Hello, John!

The call_user_func_array() function works similarly but takes the function name as the first argument and an array of arguments to be passed to the function as the second argument.


function add($a, $b) {
    return $a + $b;

$functionName = 'add';
$args = [5, 10];
$result = call_user_func_array($functionName, $args); // Output: 15

2. Using Callable Arrays

PHP allows you to use an array to call functions dynamically, wherein the first element of the array represents the object or class name (if the function is a method) and the second element represents the function name.

class MathOperations {
    public static function multiply($a, $b) {
        return $a * $b;

$functionArray = ['MathOperations', 'multiply'];
$result = call_user_func_array($functionArray, [3, 4]); // Output: 12

When using dynamic function calls, you need to ensure that the function exists and can be accessed. If you’re dealing with user input or external data to determine the function name, always validate the input to prevent security issues like code injection.

Dynamic function calls can be powerful but use them carefully as they can make your code harder to read and maintain.