Take Test: Symfony 7 – PHP – Anonymous Functions and Closures

Question 1: What is an anonymous function in PHP?

A function automatically executed on load.

A method declared static.

A function without a name, often stored in a variable or passed around.

A function declared in the global namespace.

Question 2: Which syntax defines an anonymous function?

$f = function($x) { return $x * 2; };

function f($x) => $x * 2;

$f = new function($x) { return $x; };

lambda($x) { return $x; }

Question 3: What keyword allows an anonymous function to use variables from outside its scope?

import

capture

use

include

Question 4: What will this code print? $y=10; $f=function($x) use($y){return $x+$y;}; echo $f(5);

10

15

5

Error: undefined variable.

Question 5: How can a closure modify an external variable?

By declaring it global.

By redefining it inside the closure.

By passing it as a parameter implicitly.

By importing it with use(&$var).

Question 6: What happens if you modify $y after defining the closure? $y=5; $f=function() use($y){return $y;}; $y=10; echo $f();

5

10

Undefined variable.

Fatal error.

Question 7: What does Closure::bind() allow you to do?

Copy the closure code to another file.

Clone the closure as a new function.

Rebind a closure to another object and scope.

Convert the closure into a class.

Question 8: What will this output? $x=3; $y=function() use($x){return $x*2;}; echo $y();

6

3

Fatal error

Nothing

Question 9: What is returned by function test(){return function($x){return $x+1;};}?

An integer.

Nothing.

A syntax error.

A Closure object.

Question 10: What will echo here? $a=function($n){return $n*$n;}; echo $a(4);

8

16

Syntax error

Nothing

Question 11: What does Closure::fromCallable([$obj, "method"]) do?

Creates a new anonymous class.

Executes the callable immediately.

Converts a callable into a Closure object.

Returns a string representation.

Question 12: What’s the main difference between anonymous functions and arrow functions (fn)?

Arrow functions must use use() explicitly.

Arrow functions capture by reference only.

Arrow functions cannot access outer scope.

Arrow functions automatically capture variables by value and use a single expression.

Question 13: What will this print? $x=5; $f=fn($y)=>$x+$y; echo $f(3);

5

3

8

Error: undefined variable.

Question 14: Which type does every anonymous function return when created?

FunctionObject

Callable

Closure

ObjectFunction

Question 15: What is the purpose of Closure::call($object)?

It copies the closure to another class.

It invokes the closure in the context of the given object.

It serializes the closure for transport.

It prevents scope binding.

Question 16: What is printed? $a=1;$f=function()use(&$a){$a++;};$f();echo $a;

2

1

Error

Nothing

Question 17: What is true about closures inside loops?

They all share the same variable reference by default.

They cannot be used inside loops.

They capture the variable as it exists at definition time.

They are automatically static.

Question 18: What does the keyword static mean inside an anonymous function?

It makes all variables global.

It prevents binding to $this, making the closure independent.

It forces variables to be captured by reference.

It disables variable imports via use.

Question 19: What’s the output? function get(){return function(){return "Hello";};} $a=get(); echo $a();

Nothing

Error

Hi

Hello

Question 20: Why are closures useful for callbacks and array functions (like array_map)?

They automatically optimize performance.

They require no parameters.

They can be defined inline and passed directly as callbacks.

They are required in all loops.