Description
array array_map ( callback $callback, array $arr1 [, array $...] )array_map() returns an array containing all the elements of arr1 after applying the callback function to each one. The number of parameters that the callback function accepts should match the number of arrays passed to the array_map()
Parameters
- callback
- Callback function to run for each element in each array.
- arr1
- An array to run through the callback function.
- array
- Variable list of array arguments to run through the callback function.
Return Values
Returns an array containing all the elements of arr1 after applying the callback function to each one.Examples
Example 252. array_map() example
<?phpfunction cube($n)
{
return($n * $n * $n);
}
$a = array(1, 2, 3, 4, 5);$b = array_map("cube", $a);print_r($b);?> This makes $b have: Array
(
[0] => 1
[1] => 8
[2] => 27
[3] => 64
[4] => 125
)
Examples
Example 253. array_map() - using more arrays
function show_Spanish($n, $m)
{
return("The number $n is called $m in Spanish");
}
function map_Spanish($n, $m)
{
return(array($n => $m));
}
$a = array(1, 2, 3, 4, 5);$b = array("uno", "dos", "tres", "cuatro", "cinco");
$c = array_map("show_Spanish", $a, $b);print_r($c);
$d = array_map("map_Spanish", $a , $b);print_r($d);
// printout of $c
Array
(
[0] => The number 1 is called uno in Spanish
[1] => The number 2 is called dos in Spanish
[2] => The number 3 is called tres in Spanish
[3] => The number 4 is called cuatro in Spanish
[4] => The number 5 is called cinco in Spanish
)
// printout of $d
Array
(
[0] => Array
(
[1] => uno
)
[1] => Array
(
[2] => dos
)
[2] => Array
(
[3] => tres
)
[3] => Array
(
[4] => cuatro
)
[4] => Array
(
[5] => cinco
)
) Usually when using two or more arrays, they should be of equal length because the callback function is applied in parallel to the corresponding elements. If the arrays are of unequal length, the shortest one will be extended with empty elements.
An interesting use of this function is to construct an array of arrays, which can be easily performed by using NULL as the name of the callback function
Example 254. Creating an array of arrays
$a = array(1, 2, 3, 4, 5);$b = array("one", "two", "three", "four", "five");$c = array("uno", "dos", "tres", "cuatro", "cinco");
$d = array_map(null, $a, $b, $c);print_r($d);
Array
(
[0] => Array
(
[0] => 1
[1] => one
[2] => uno
)
[1] => Array
(
[0] => 2
[1] => two
[2] => dos
)
[2] => Array
(
[0] => 3
[1] => three
[2] => tres
)
[3] => Array
(
[0] => 4
[1] => four
[2] => cuatro
)
[4] => Array
(
[0] => 5
[1] => five
[2] => cinco
)
)
