PHP Array_walk Each element in an array using user-defined functions to explain _php instances

PHP array_walk Apply user-defined functions to each element in an array

Array_walk use user-defined functions to do callback for each element in the array

Basic syntax

BOOL Array_walk (array & $array, callable $funcname [, mixed $userdata = NULL])

Applies the user-defined function funcname to each cell in an array.

Array_walk () is not affected by array pointers within the array. Array_walk () traverses the entire array regardless of the position of the pointer.

Parameter introduction:

Parameters	Description
Array	Necessary. The array entered.
Funname	Necessary. The name of the user-defined function. Typically, the funcname accepts two parameters. The value of the array parameter is the first, and the key name is the second. If funcname needs to act directly on the values in the array, the first argument to FuncName is specified as a reference. Any changes to these units will also change the original array itself.
UserData	Optional. Specify the parameters of the user-defined function. If an optional parameter userdata is provided, it is passed as the third argument to callback funcname.

Description

The 1.array_walk () function applies a callback function to each element in the array. Returns TRUE if successful, otherwise returns FALSE.

2. Typically, the Funname accepts two parameters. The value of the array parameter is the first, and the key name is the second. If an optional parameter userdata is provided, it is passed as the third argument to the callback function.

3. If the Funname function requires more arguments than is given, a e_warning-level error will be generated each time the Array_walk () call Funname. These warnings can be suppressed by adding PHP's error operator @ before the Array_walk () call, or by using error_reporting ().

4. If the callback function needs to act directly on the value in the array, you can specify the first argument of the callback function as a reference.

return value

Returns TRUE on success or FALSE on failure.

Instance:

<?php
$fruits = Array (
  "D" => "Lemon",
  "a" => "orange",
  "B" => "banana",
  "C" => " Apple "
);
Function Test_alter (& $item 1, $key, $prefix) {
  $item 1 = "$prefix: $item 1";
}
function Test_print ($item 2, $key) {
  echo $key. $item 2 <br/> ";
}
echo "before ...: <br/>";
Array_walk ($fruits, ' test_print ');
Array_walk ($fruits, ' test_alter ', ' fruit ');
echo "... and after:<br/>";
Array_walk ($fruits, ' test_print ');
? > 

Run Result:

Before ...:
D. Lemon
A. Orange
B. Banana
C. Apple
.. and After:
D. Fruit:lemon
A. Fruit:orange
B. Fruit:banana
C. Fruit:apple

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