Array Short Functions
PHP provides several array short functions that allow for concise and efficient manipulation of arrays. These include commonly used functions for filtering, mapping, reducing, and other operations. Let's explore some of the most important ones:
1. array_map()
Purpose: Applies a callback function to each element of one or more arrays, returning a new array with the results.
Syntax:
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array array_map(callable $callback, array $array, ...$arrays)
Example:
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$numbers = [1, 2, 3, 4];
$squared = array_map(fn($n) => $n * $n, $numbers);
print_r($squared);
Output:
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Array
(
[0] => 1
[1] => 4
[2] => 9
[3] => 16
)
2. array_filter()
Purpose: Filters elements of an array using a callback function. It returns an array containing only the elements for which the callback returns true.
Syntax:
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array array_filter(array $array, callable $callback = null, int $mode = 0)
Example:
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$numbers = [1, 2, 3, 4, 5];
$even = array_filter($numbers, fn($n) => $n % 2 == 0);
print_r($even);
Output:
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Array
(
[1] => 2
[3] => 4
)
3. array_reduce()
Purpose: Iteratively reduces an array to a single value using a callback function.
Syntax:
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mixed array_reduce(array $array, callable $callback, mixed $initial = null)
Example:
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$numbers = [1, 2, 3, 4];
$sum = array_reduce($numbers, fn($carry, $n) => $carry + $n, 0);
echo $sum;
Output:
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10
4. array_walk()
Purpose: Applies a callback function to each element of an array, modifying the array in-place. It doesn't return a new array but modifies the original.
Syntax:
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bool array_walk(array &$array, callable $callback, mixed $userdata = null)
Example:
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$numbers = [1, 2, 3];
array_walk($numbers, fn(&$n) => $n *= 2);
print_r($numbers);
Output:
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Array
(
[0] => 2
[1] => 4
[2] => 6
)
5. array_merge()
Purpose: Merges one or more arrays into a single array.
Syntax:
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array array_merge(array ...$arrays)
Example:
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$array1 = [1, 2];
$array2 = [3, 4];
$merged = array_merge($array1, $array2);
print_r($merged);
Output:
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Array
(
[0] => 1
[1] => 2
[2] => 3
[3] => 4
)
6. array_key_exists()
Purpose: Checks if a specified key or index exists in an array.
Syntax:
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bool array_key_exists(mixed $key, array $array)
Example:
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$array = ['name' => 'John', 'age' => 25];
if (array_key_exists('age', $array)) {
echo "Key exists!";
}
Output:
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Key exists!
7. array_keys() and array_values()
Purpose:
array_keys() returns all the keys from an array.
array_values() returns all the values from an array.
Syntax:
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array array_keys(array $array)
array array_values(array $array)
Example:
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$array = ['name' => 'John', 'age' => 25];
print_r(array_keys($array)); // Outputs keys
print_r(array_values($array)); // Outputs values
Output:
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Array
(
[0] => name
[1] => age
)
Array
(
[0] => John
[1] => 25
)
8. array_slice()
Purpose: Extracts a portion of an array and returns it as a new array.
Syntax:
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array array_slice(array $array, int $offset, int $length = null, bool $preserve_keys = false)
Example:
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$array = [1, 2, 3, 4, 5];
$slice = array_slice($array, 2);
print_r($slice);
Output:
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Array
(
[0] => 3
[1] => 4
[2] => 5
)
9. array_unique()
Purpose: Removes duplicate values from an array.
Syntax:
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array array_unique(array $array, int $flags = SORT_STRING)
Example:
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$array = [1, 2, 2, 3, 3, 4];
$unique = array_unique($array);
print_r($unique);
Output:
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Array
(
[0] => 1
[1] => 2
[3] => 3
[5] => 4
)
These array functions are very useful for manipulating and processing data efficiently in PHP.
