Home > Backend Development > PHP Tutorial > PHP array function array_walk() notes_PHP tutorial

PHP array function array_walk() notes_PHP tutorial

WBOY
Release: 2016-07-13 10:17:13
Original
990 people have browsed it

PHP array function array_walk() notes

Definition and usage

The array_walk() function applies a callback function to each element in the array. Returns TRUE if successful, FALSE otherwise.

Typically function accepts two parameters. The value of array parameter is used as the first one, and the key name is used as the second one. If the optional parameter userdata is provided, it will be passed to the callback function as the third parameter.

If function requires more arguments than given, an E_WARNING level error will be generated each time array_walk() calls function. These warnings can be suppressed by preceding the array_walk() call with PHP's error operator @, or by using error_reporting().

Grammar

array_walk(array,function,userdata...)

参数 描述
array 必需。规定数组。
function 必需。用户自定义函数的名称。
userdata 可选。用户输入的值,可作为回调函数的参数。

Tips and Notes

Tip: You can set one or more parameters for the function.

Note: If the callback function needs to act directly on the values ​​in the array, you can specify the first parameter of the callback function as a reference: &$value. (see example 3)

Note: Passing key name and userdata into function is new in PHP 4.0.

Example 1

1

2

3

4

5

6

7

<?php

function myfunction($value, $key) {

    echo "The key $key has the value $value<br />";

}

 

$a = array("a" => "Cat", "b" => "Dog", "c" => "Horse");

array_walk($a, "myfunction");

Copy after login

Output:

The key a has the value Cat
The key b has the value Dog
The key c has the value Horse

Example 2

takes one parameter:

1

2

3

4

5

6

7

8

<?php

function myfunction($value, $key, $p) {

    echo "$key $p $value<br />";

}

 

$a = array("a" => "Cat", "b" => "Dog", "c" => "Horse");

array_walk($a, "myfunction", "has the value");

?>

Copy after login

Output:

a has the value Cat
b has the value Dog
c has the value Horse

Example 3

Change the value of the array element (please note &$value): (This is used more often!)

1

2

3

4

5

6

7

8

<?php

function myfunction(&$value, $key) {

    $value = "Bird";

}

 

$a = array("a" => "Cat", "b" => "Dog", "c" => "Horse");

array_walk($a, "myfunction");

print_r($a);

Copy after login

Output:

Array ( [a] => Bird [b] => Bird [c] => Bird )

Articles you may be interested in

  • PHP array function array_map() notes
  • PHP generates continuous numeric (letter) array function range() analysis, PHP Lottery program function
  • php searches whether a value exists in the array (in_array(), array_search(), array_key_exists())
  • php pushes elements to the head of the array (usage of array_unshift )
  • PHP removes null elements from arrays (array_filter)
  • How to delete elements from PHP arrays (unset, array_splice)?
  • Introduction to the union, intersection and difference functions of arrays in php
  • Use the PHP function memory_get_usage to obtain the current PHP memory consumption to optimize the performance of the program

www.bkjia.comtruehttp: //www.bkjia.com/PHPjc/894481.htmlTechArticlePHP array function array_walk() notes definition and usage array_walk() function applies a callback function to each element in the array . Returns TRUE if successful, FALSE otherwise. Typically...
Related labels:
source:php.cn
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template