array_map
Applies the callback to the elements of the given arrays
&reftitle.description;
arrayarray_map
callablenullcallback
arrayarray
arrayarrays
array_map returns an &array; containing
the results of applying the callback
to the corresponding index of array
(and arrays if more arrays are provided)
used as arguments for the callback.
The number of parameters that the callback
function accepts should match the number of arrays
passed to array_map.
&reftitle.parameters;
callback
A callable to run for each element in each array.
&null; can be passed as a value to callback
to perform a zip operation on multiple arrays.
If only array is provided,
array_map will return the input array.
array
An array to run through the callback function.
arrays
Supplementary variable list of array arguments to run through the
callback function.
&reftitle.returnvalues;
Returns an array containing the results of applying the callback
function to the corresponding index of array
(and arrays if more arrays are provided)
used as arguments for the callback.
The returned array will preserve the keys of the array argument if and only
if exactly one array is passed. If more than one array is passed, the
returned array will have sequential integer keys.
&reftitle.examples;
<function>array_map</function> example
]]>
This makes $b have:
1
[1] => 8
[2] => 27
[3] => 64
[4] => 125
)
]]>
<function>array_map</function> using a lambda function (as of PHP 5.3.0)
]]>
2
[1] => 4
[2] => 6
[3] => 8
[4] => 10
)
]]>
<function>array_map</function> - using more arrays
$m];
}
$a = [1, 2, 3, 4, 5];
$b = ['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);
?>
]]>
&example.outputs;
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 $d
Array
(
[0] => Array
(
[1] => uno
)
[1] => Array
(
[2] => dos
)
[2] => Array
(
[3] => tres
)
[3] => Array
(
[4] => cuatro
)
[4] => Array
(
[5] => cinco
)
)
]]>
Usually when using two or more arrays, they should be of equal length
because the callback function is applied in parallel to the corresponding
elements.
If the arrays are of unequal length, shorter ones will be extended with empty
elements to match the length of the longest.
An interesting use of this function is to construct an array of arrays,
which can be easily performed by using &null;
as the name of the callback function
Performing a zip operation of arrays
]]>
&example.outputs;
Array
(
[0] => 1
[1] => one
[2] => uno
)
[1] => Array
(
[0] => 2
[1] => two
[2] => dos
)
[2] => Array
(
[0] => 3
[1] => three
[2] => tres
)
[3] => Array
(
[0] => 4
[1] => four
[2] => cuatro
)
[4] => Array
(
[0] => 5
[1] => five
[2] => cinco
)
)
]]>
&null; <parameter>callback</parameter> with only
<parameter>array</parameter>
]]>
&example.outputs;
int(1)
[1]=>
int(2)
[2]=>
int(3)
}
]]>
<function>array_map</function> - with string keys
'value'];
function cb1($a) {
return [$a];
}
function cb2($a, $b) {
return [$a, $b];
}
var_dump(array_map('cb1', $arr));
var_dump(array_map('cb2', $arr, $arr));
var_dump(array_map(null, $arr));
var_dump(array_map(null, $arr, $arr));
?>
]]>
&example.outputs;
array(1) {
[0]=>
string(5) "value"
}
}
array(1) {
[0]=>
array(2) {
[0]=>
string(5) "value"
[1]=>
string(5) "value"
}
}
array(1) {
["stringkey"]=>
string(5) "value"
}
array(1) {
[0]=>
array(2) {
[0]=>
string(5) "value"
[1]=>
string(5) "value"
}
}
]]>
&reftitle.seealso;
array_filter
array_reduce
array_walk