Defining and calling functions in PHP Mocktest

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.

Anonymous functions in PHP, also known as closures, 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.

Variables defined inside a function have local scope in PHP, meaning they are only accessible within that function. Variables defined outside of any function have global scope and can be accessed from anywhere in the script.

The output of the code will be 10 because the $num variable is declared as global inside the testScope() function using the global keyword, allowing it to access the global variable with the same name declared outside the function.

Callbacks in PHP allow passing a function as an argument to another function, providing flexibility and enabling advanced programming techniques such as event handling and functional programming paradigms.

The output of the code will be HELLO because the uppercase() function accepts a string $str as a parameter and returns its uppercase version using the strtoupper() function. The function is then called with the argument "hello" and its result is 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.

The function_exists() function in PHP is used to check if a function exists before calling it, helping to avoid errors and ensuring code reliability.

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!".