PHP · December 19, 2023

Php Tip: Use array_map() to applies the callback to the elements of the given arrays

Php Tip: Use array_map() to apply the callback to the elements of the given arrays

When it comes to working with arrays in PHP, developers often find themselves needing to perform operations on each element of an array. This can be a tedious task, especially when dealing with large arrays. However, PHP provides a handy function called array_map() that can simplify this process and make your code more efficient.

What is array_map()?

array_map() is a built-in PHP function that applies a callback function to each element of one or more arrays and returns a new array containing the results. It takes two or more parameters: the callback function and one or more arrays to iterate over.

The callback function is applied to each element of the arrays, and the results are collected into a new array. The number of parameters the callback function accepts should match the number of arrays passed to array_map(). The callback function can be any valid PHP callable, such as a function name, an anonymous function, or a method of an object.

How to use array_map()

Let's take a look at a simple example to understand how array_map() works:

$numbers = [1, 2, 3, 4, 5];

// Define a callback function
function square($n) {
    return $n * $n;
}

// Apply the callback function to each element of the array
$squared_numbers = array_map('square', $numbers);

print_r($squared_numbers);

In this example, we have an array of numbers. We define a callback function called square() that takes a number as input and returns its square. We then use array_map() to apply the square() function to each element of the $numbers array. The result is a new array $squared_numbers containing the squared values of the original numbers.

The output of the above code will be:

Array
(
    [0] => 1
    [1] => 4
    [2] => 9
    [3] => 16
    [4] => 25
)

Applying the callback to multiple arrays

array_map() can also be used to apply the callback function to multiple arrays simultaneously. The callback function should accept as many parameters as there are arrays passed to array_map(). Let's see an example:

$numbers1 = [1, 2, 3];
$numbers2 = [4, 5, 6];

// Define a callback function
function add($a, $b) {
    return $a + $b;
}

// Apply the callback function to each pair of elements from the arrays
$sums = array_map('add', $numbers1, $numbers2);

print_r($sums);

In this example, we have two arrays $numbers1 and $numbers2. We define a callback function called add() that takes two numbers as input and returns their sum. We use array_map() to apply the add() function to each pair of elements from the two arrays. The result is a new array $sums containing the sums of the corresponding elements from the original arrays.

The output of the above code will be:

Array
(
    [0] => 5
    [1] => 7
    [2] => 9
)

Conclusion

array_map() is a powerful function in PHP that allows you to apply a callback function to each element of one or more arrays. It simplifies the process of iterating over arrays and performing operations on their elements. By using array_map(), you can make your code more concise and efficient.

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