I'm currently using array_map to apply callbacks to elements of an array. But I want to be able to pass an argument to the callback function like array_walk does.
I suppose I could just use array_walk, but I need the return value to be an array like if you use array_map, not TRUE or FALSE.
So is it possible to use array_map and pass an argument to the callback function? Or perhaps make the array_walk return an array instead of boolean?
You don't need it to return an array.
Instead of:
$newArray = array_function_you_are_looking_for($oldArray, $funcName);
It's:
$newArray = $oldArray;
array_walk($newArray, $funcName);
array_walk the return value will be TRUE of FALSE. I want the return value to be an array like how array_map does. So either find a way to pass an argument using array_map or find a way so that array_walk return array instead of boolean.
array_walk edit the original array on which it is called? Because if it does, this is pretty sweet.
$arr = array_walk($newArray, $funcName); TRUE simply means 'it worked' and you can use the array that you inserted.array_walk, and it only modified the original array if the "walker" function that I defined used the & symbol: function walker(&$val) { ... }If you want return value is an array, just use array_map. To add additional parameters to array_map use "use", ex:
array_map(function($v) use ($tmp) { return $v * $tmp; }, $array);
or
array_map(function($v) use ($a, $b) { return $a * $b; }, $array);
Depending on what kind of arguments you need to pass, you could create a wrapped function:
$arr = array(2, 4, 6, 8);
function mapper($val, $constant) {
return $val * $constant;
}
$constant = 3;
function wrapper($val) {
return mapper($val, $GLOBALS['constant']);
}
$arr = array_map('wrapper', $arr);
This actually seems too simple to be true. I suspect we'll need more context to really be able to help.
To expand a bit on Hieu's great answer, you can also use the $key => $value pairs of the original array. Here's an example with some code borrowed from comment section http://php.net/manual/en/function.array-map.php
The following will use 'use' and include an additional parameter which is a new array.
Below code will grab "b_value" and "d_value" and put into a new array $new_arr (useless example to show a point)
// original array
$arr = ("a" => "b_value",
"c" => "d_value");
// new array
$new_arr = array();
array_map(function($k,$v) use (&$new_arr) { $new_arr[] = $v;}, array_keys($arr), $arr);
^ $k is key and $v is value
print_r of $new_arr is
Array
(
[0] => b_value
[1] => d_value
)
