How to use array_walk() function in PHP? (code example)

The array_walk() function is a built-in function in PHP. Regardless of the pointer position, the array_walk() function will traverse the entire array and perform specified callback processing on each element of the array; the keys and values ​​of the array elements are parameters in the callback function.

Syntax:

array_walk($array, myFunction, $extraParam)

Parameter description: array_walk() function accepts The following three parameters

●$array: used to specify the input array and pass the target array. This parameter cannot be omitted (required).

● MyFunction: Used to specify the name of the user-defined function. This parameter is also non-omitable (required). User-defined functions usually include two parameters, where the first parameter represents the value of the array, and the second parameter represents the corresponding key.

●$ extraparam: This is an optional parameter and can be omitted; used to specify another extra parameter in addition to the two parameters (array key and value) of the user-defined function.

Return value: array_walk() function returns a Boolean value. Returns TRUE on success and FALSE on failure.

Example 1:

<?php 
header("content-type:text/html;charset=utf-8");
// 自定义回调函数
function myfunction($value, $key) 
{ 
 echo "键 $key 的值为 $value "."<br>"; 
} 
  
// 定义数组
$arr = array("a"=>"yellow", "b"=>"pink", "c"=>"purple"); 
  
// 没有额外参数的调用Array_walk（）
array_walk($arr, "myfunction"); 
  
?>

Output:

Example 2:

<?php 
header("content-type:text/html;charset=utf-8");
// 自定义回调函数
function myfunction($value, $key, $extraParam) 
{ 
    echo "$key $extraParam $value "."<br>"; 
} 
  
// 定义数组
$arr = array("green"=>"绿色", "pink"=>"粉红色", "blue"=>"蓝色"); 
  
// 有额外参数的调用Array_walk（）
array_walk($arr, "myfunction", "表示："); 
  
?>

Output:

##Example 3:

<?php 
// 自定义回调函数
function myfunction(&$value, $key) 
{ 
    $value = $value + 10; 
} 
  
// 定义函数
$arr = array("first"=>10, "second"=>20, "third"=>30); 
  
//没有额外参数的调用Array_walk（）
array_walk($arr, "myfunction"); 
  
// 更新值后输出数组
var_dump($arr); 
  
?>

Output:

Description: By using "&$value" to specify the first parameter in the user-defined function as a reference, it can be changed The value of the array element.

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