How to apply callback function for each element of array in PHP

php editor Xigua will introduce you how to use the array_map() function to apply a callback function to each element of the array. The array_map() function can execute a callback function on each element in the array and return a new array, realizing batch processing of array elements. Through simple examples and detailed explanations, this article will help you quickly master how to use the array_map() function in PHP to process elements in an array and improve your programming efficiency.

Use callback function to process array elements in php

Introduction

The array_map() function in

php allows you to apply a callback function to each element in an array. It can greatly simplify the task of performing complex operations on array elements.

grammar

array_map(callable $callback, array $array): array

parameter

• $callback: The name of the callback function or anonymous function.
• $array: The array to be processed.

return value

A new array in which each element is processed through the callback function.

Example

Add 1 to all numbers in the array

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

$incremented_numbers = array_map(function ($number) {
return $number 1;
}, $numbers);

// Output: [2, 3, 4, 5, 6]

Extract specific attributes of objects in the array

class Person {
public $name;
public $age;
}

$people = [
new Person("John", 30),
new Person("Mary", 25),
new Person("Bob", 40),
];

$names = array_map(function ($person) {
return $person->name;
}, $people);

// Output: ["John", "Mary", "Bob"]

Advanced usage

Multi-parameter callback function

The callback function can accept multiple parameters, including the parameters of the callback function and the index or key of the array.

$mixed_array = [1, "string", true, null];

$result = array_map(function ($element, $index) {
return "Element $index: $element";
}, $mixed_array, array_keys($mixed_array));

// Output: ["Element 0: 1", "Element 1: string", "Element 2: 1", "Element 3: NULL"]

Anonymous function

You can define anonymous functions directly in the array_map() function without creating a separate function.

$result = array_map(function ($value) {
return strtoupper($value);
}, $array);

Use external variables

Callback functions can access external variables, but you need to capture them explicitly using the use keyword.

$add_value = 10;

$result = array_map(function ($value) use ($add_value) {
return $value $add_value;
}, $array);

Best Practices

• Use descriptive callback function names to improve code readability.
• Consider using anonymous functions to implement simple operations.
• If you want to use external variables, make sure to capture them explicitly using the use keyword.
• Avoid performing complex or time-consuming operations in callback functions as it will affect performance.

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