PHP array function array_map() notes_PHP tutorial

PHP array function array_map() notes

Definition and usage

The array_map() function returns the array after the user-defined function is applied. The callback function should accept the same number of arguments as the number of arrays passed to the array_map() function.

Grammar

array_map(function,array1,array2,array3...)

参数	描述
function	必需。用户自定义函数的名称，或者是 null。
array1	必需。规定数组。
array2	可选。规定数组。
array3	可选。规定数组。

Example 1

<?php
function myfunction($v) {
	if ($v === "Dog") {
		return "Fido";
	}
	return $v;
}

$a = array("Horse", "Dog", "Cat");
print_r(array_map("myfunction", $a));
?>

Output:

Array ( [0] => Horse [1] => Fido [2] => Cat )

Example 2

Use multiple parameters:

<?php
function myfunction($v1, $v2) {
	if ($v1 === $v2) {
		return "same";
	}
	return "different";
}

$a1 = array("Horse", "Dog", "Cat");
$a2 = array("Cow", "Dog", "Rat");
print_r(array_map("myfunction", $a1, $a2));
?>

Output:

Array ( [0] => different [1] => same [2] => different )

Example 3

Please see what happens when the custom function name is set to null:

<?php
$a1 = array("Dog", "Cat");
$a2 = array("Puppy", "Kitten");
print_r(array_map(null, $a1, $a2));
?>

Output:

Array (
[0] => Array ( [0] => Dog [1] => Puppy )
[1] => Array ( [0] => Cat [1] => Kitten )
)

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