Arrow functions (short closures) in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an arrow function in PHP?

An arrow function is a short way to write anonymous functions using the fn keyword. It automatically captures variables from the parent scope without needing the 'use' keyword.

beginner

How do arrow functions capture variables from the parent scope?

Arrow functions automatically capture variables from the parent scope by value, so you don't need to specify them with 'use'.

beginner

Rewrite this anonymous function as an arrow function:<br>

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

$double = fn($x) => $x * 2;

intermediate

Can arrow functions contain multiple statements in PHP?

No, arrow functions can only contain a single expression. For multiple statements, use a regular anonymous function.

intermediate

What is the difference between arrow functions and regular anonymous functions in PHP?

Arrow functions use the fn keyword, have implicit returns, and automatically capture variables by value. Regular anonymous functions use the function keyword and require 'use' to access variables from the parent scope.

Which keyword is used to declare an arrow function in PHP?

A fn

B function

C arrow

D lambda

Arrow functions in PHP are declared using the 'fn' keyword.

How do arrow functions capture variables from the parent scope?

A You must specify variables with 'use'

B Automatically by reference

C Automatically by value

D They cannot access parent scope variables

Arrow functions automatically capture variables from the parent scope by value.

Can arrow functions contain multiple statements in PHP?

A Yes, with curly braces

B Yes, if you use 'return'

C Only if declared inside a class

D No, only a single expression

Arrow functions can only contain a single expression; multiple statements require regular anonymous functions.

What does this arrow function return?<br>

$add = fn($a, $b) => $a + $b;<br>echo $add(3, 4);

A 7

B 34

C Error

D null

The arrow function adds 3 and 4, returning 7.

Which of the following is true about arrow functions compared to regular anonymous functions?

A Arrow functions require 'use' to access variables

B Arrow functions have implicit return

C Arrow functions can have multiple statements

D Arrow functions cannot access parent scope variables

Arrow functions have implicit return and automatically capture variables by value.

Explain how arrow functions differ from regular anonymous functions in PHP.

Think about syntax and how variables are accessed.

Write a simple arrow function in PHP that multiplies a number by 5.

Use fn(parameter) => expression;