parameter

• array (required): The input array that needs to be filtered.
• callback (optional): A callback function that handles each element in the array. If this parameter is not provided, all elements whose value is not false will be retained.
• mode (optional): This parameter specifies the parameter of the callback function. 0 (default) means using array values as parameters of the callback function, and 1 means using array keys as parameters of the callback function.

Return value

Returns the filtered array. If there are no elements that meet the criteria, return an empty array.

Example

// Example 1: Filter out empty values in array
$array = [0, 1, 2, null, false, '', 3, 'hello'];
$result = array_filter($array);
print_r($result);

// Output:
// Array
// (
// [1] => 1
// [2] => 2
// [6] => 3
// [7] => hello
// )

// Example 2: Filtering with a custom callback function
$array = [1, 2, 3, 4, 5];
$result = array_filter($array, function($value) {
return $value % 2 == 0; // Only even numbers are retained
});
print_r($result);

// Output:
// Array
// (
// [1] => 2
// [3] => 4
// )

<h2>Description of sample code</h2>
<p>In the first example, the array_filter function is used to filter out all "false" values (such as 0, null, false, and empty strings). This example shows how to preserve only all valid array values.</p>

<p>In the second example, a custom callback function is used to filter out all elements that are not even numbers. This example demonstrates how to use callback functions to perform more complex filtering of array elements.</p>