Passing arguments to functions and returning values Mocktest

The output of the code will be Hello, World! because the function_exists() function checks if the function greet() exists before calling it. Since the function does exist, it is called and echoes Hello, World!.

Varargs (variable-length argument lists) in PHP allow defining functions with a variable number of arguments. This feature is achieved using the ...$args syntax in the function definition, allowing the function to accept any number of arguments.

The output of the code will be 24 because the multiply() function takes a variable number of arguments using the ...$args syntax and multiplies them together using a foreach loop. The function is then called with arguments 2, 3, and 4, resulting in the product of 2 * 3 * 4 = 24 being echoed.

Passing functions as arguments in PHP enables dynamic function invocation and behavior, allowing for more flexible and powerful programming constructs such as callbacks and higher-order functions.

Anonymous functions (also known as closures) in PHP allow defining functions without specifying their names. They can be assigned to variables or passed as arguments to other functions.

The output of the code will be Hello, John! because the anonymous function assigned to the variable $greet accepts a parameter $name and returns the string "Hello, $name!" with the provided value substituted in. The function is then called with the argument "John" and its result is echoed.

Nested functions in PHP allow defining functions within other functions, enabling encapsulation and modularization of code by restricting the scope of inner functions to their parent functions.

The output of the code will be Function does not exist: inner because the inner function inner() is defined within the outer() function and is not accessible outside of it. Attempting to call inner() directly results in an error since it is not defined in the global scope.

Variable arguments (also known as varargs) in PHP allow defining functions with a variable number of arguments. This feature is achieved using the ...$args syntax in the function definition, allowing the function to accept any number of arguments.

The output of the code will be 120 because the factorial() function calculates the factorial of a number $n using a loop and returns the result. The function is then called with the argument 5, resulting in the factorial of 5 (5!) being echoed to the output.