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PHP array_map() Function

Quick summary: The PHP array_map() function applies a callback to each element of an array.

PHP array_map() Syntax 

array_map(?callable $callback, array $array, array ...$arrays): array
PHP

PHP array_map() Basic examples 

$nums = [1, 2, 3];
$result = array_map(fn($n) => $n * 2, $nums);
var_dump($result);
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Output:
array(3) {
  [0]=> int(2)
  [1]=> int(4)
  [2]=> int(6)
}

Transforms each array element.

PHP array_map() Real-world usage 

$names = [" alice ", " bob "];
$clean = array_map('trim', $names);
var_dump($clean);
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Output:
array(2) {
  [0]=> string(5) "alice"
  [1]=> string(3) "bob"
}

Cleans user input values.

PHP array_map() Edge cases 

var_dump(array_map(null, [1,2], [3,4]));
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Output:
array(2) {
  [0]=> array(2) { [0]=> int(1) [1]=> int(3) }
  [1]=> array(2) { [0]=> int(2) [1]=> int(4) }
}

Combines arrays when callback is null.

PHP array_map() Common mistakes

Using array_map for filtering

array_map does not remove elements.

Incorrect
array_map(fn($v) => $v > 2, [1,2,3]);
Correct
array_filter([1,2,3], fn($v) => $v > 2);

Use array_filter when removing elements.

PHP array_map() Frequently Asked Questions

What does array_map() do in PHP?

array_map() applies a callback function to each element of an array and returns a new array.

What is the syntax of array_map()?

array_map(callable $callback, array $array, array ...$arrays): array

Does array_map() modify the original array?

No, it returns a new array and leaves the original unchanged.

Can array_map() work with multiple arrays?

Yes, it can process multiple arrays in parallel.

What happens if arrays have different lengths?

Shorter arrays are padded with null values.

Can array_map() be used without a callback?

Yes, passing null returns arrays grouped by index.

Is array_map() faster than foreach?

Performance is similar; choice depends on readability and use case.

Can array_map() handle associative arrays?

Yes, but keys are preserved only with a single array.

What is a real-world use case of array_map()?

Transforming data such as trimming, formatting, or mapping values.

Can array_map() return different data types?

Yes, the callback can return any type.

Is array_map() functional programming?

Yes, it is a functional-style approach to processing arrays.

Can array_map() be combined with other functions?

Yes, it is often used with array_filter() or array_reduce().

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