How to use arrays for conditional filtering in PHP

How to use arrays for conditional filtering in PHP

In PHP development, arrays are a very commonly used and important data structure. Conditional filtering through arrays can help us process and filter data quickly and effectively. This article will introduce how to use arrays for conditional filtering in PHP and provide relevant code examples.

1. Use foreach loop to filter

First, we can use foreach loop to traverse the array and filter the required data based on conditions. For example, we have an array $grades that contains student scores, and we want to filter out students with scores greater than 80:

$grades = array(
    'Tom' => 90,
    'Alice' => 76,
    'Bob' => 85,
    'John' => 92
);

$filteredGrades = array();

foreach ($grades as $name => $score) {
    if ($score > 80) {
        $filteredGrades[$name] = $score;
    }
}

print_r($filteredGrades);

The output result is:

Array
(
    [Tom] => 90
    [Bob] => 85
    [John] => 92
)

2. Use the array_filter function to filter

In addition to using the foreach loop, we can also use the array_filter function provided by PHP to filter. The array_filter function can receive an array and a callback function as parameters, and the callback function is used to judge the filtering conditions. For example, we can use the array_filter function to filter out students with scores greater than 80:

$filteredGrades = array_filter($grades, function($score) {
    return $score > 80;
});

print_r($filteredGrades);

The output is the same as before:

Array
(
    [Tom] => 90
    [Bob] => 85
    [John] => 92
)

3. Use the array_walk function to filter

In addition to the array_filter function, we can also use the array_walk function to filter. The array_walk function can traverse an array and operate on each element. By adding filter conditions in the callback function, we can achieve different filtering effects. For example, we can use the array_walk function to filter out students whose scores are less than 90:

$filteredGrades = array();

array_walk($grades, function($score, $name) use (&$filteredGrades) {
    if ($score < 90) {
        $filteredGrades[$name] = $score;
    }
});

print_r($filteredGrades);

The output result is:

Array
(
    [Alice] => 76
    [Bob] => 85
)

The above are three methods of using arrays for conditional filtering and their code examples. In the actual development process, selecting appropriate methods for screening based on specific needs can help us process and screen data more efficiently. Hope this article is helpful to everyone!

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