Anonymous Functions in PHP

In this article, I will explain how to create Anonymous Functions in PHP.

Anonymous functions are those functions that we create without a name. In fact, we can use anonymous functions in a number of places. For instance, suppose we need to pass a function as a parameter to another function. In such a case, first, we create an anonymous function and assign it to a variable. Then, we can pass this variable as a parameter.

Furthermore, we can also define an anonymous function at the place where it needs to be invoked. As a result, the code remains concise. Therefore, the use of anonymous functions simplifies the programs, reduces the lines of code, and eliminates the need of creating a separate file for the function definition.

Examples of Anonymous Functions in PHP

The following code shows a simple anonymous function that returns the sum of two numbers that the function takes as arguments.

<?php
$v=function($x, $y){ return $x+$y;};
echo $v(3, 4);
?>

Output

Another example of the anonymous function is shown below. As can be seen, the function array_walk() takes a function as the second parameter which is an anonymous function in this example. It computes the sum of integers from 1 to the value of a specific array element.

<?php
$arr=array(1,2,3,4,5,6,7,8,9,10);
array_walk($arr, function($n){
	$s=0;
	for($i=1;$i<=$n;$i++){
		$s+=$i;
	}
	echo 'Number: ',$n,' Sum: ',$s,'<br>';});
?>

Output

Similarly, the following PHP Script displays the factorial of each element of the array. Here also, the function that computes the factorial is passed as an argument to the array_walk() function.

<?php
$arr=array(6, 8, 12, 9, 5, 6, 4);
$factorials=function($n){
        $f=1;
	for($i=1;$i<=$n;$i++)
	{
		$f*=$i;
	}
	echo 'Factorial of ',$n,' is ',$f,'<br>';
	};
array_walk($arr, $factorials);
?>

Output

The following code shows the use of the anonymous function to find the sum of values of an array in a two-dimensional array.

<?php
$marks=array(array(78, 80, 45, 90, 30),
	array(40, 45, 67, 87, 24),
	array(28, 60, 37, 45, 73),
	array(98, 22, 45, 97, 48),
	array(37, 89, 50, 44, 85),
	array(76, 56, 87, 24, 24),
	array(90, 86, 38, 78, 74));

function Display_Result($m)
{
  foreach($m as $a)
  {
	$c=function($t) use($a){ 
                foreach($t as $k)
                {
                     echo $k.' ';
		}
		$sum=array_sum($t);
                $p=($sum*100)/500;
                echo 'Percentage: '.$p.'<br>'; 
        };
        
  }
  array_walk($m, $c);
}
Display_Result($marks);
?>

Output

Further Reading

Examples of Array Functions in PHP

Basic Programs in PHP

Registration Form Using PDO in PHP

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