Advanced sorting of PHP arrays: custom comparators and anonymous functions

In PHP, there are two ways to sort an array in a custom order: Custom comparator: implement the Comparable interface and specify the comparison rules of the two objects. Anonymous function: Create an anonymous function as a custom comparator to compare two objects against a criterion.

PHP Array Advanced Sorting: Custom Comparator and Anonymous Function

In PHP, sort arrays in custom order Sorting requires functionality beyond what the standard sort functions can provide. Custom comparators and anonymous functions provide a more flexible sorting mechanism than built-in functions such as sort() and rsort().

Custom comparator

A custom comparator is a class that implements the Comparable interface, which defines how to compare two objects. Implement the compareTo() method to specify which object is considered greater than, less than, or equal to another object.

class CustomComparator implements Comparable {
    public function compareTo($a, $b): int {
        if ($a == $b) {
            return 0;
        }
        return $a > $b ? 1 : -1;
    }
}

Anonymous functions

Anonymous functions are unnamed functions that can be created on the fly and passed as arguments. They are often used to create custom comparators:

$comparator = function($a, $b) {
    if ($a == $b) {
        return 0;
    }
    return $a > $b ? 1 : -1;
};

Practical example

Consider an array containing student names and scores:

$students = [
    ['name' => 'Alice', 'score' => 85],
    ['name' => 'Bob', 'score' => 90],
    ['name' => 'Carol', 'score' => 80],
];

Custom comparator method

$comparator = new CustomComparator();
usort($students, [$comparator, 'compareTo']);

Anonymous function method

usort($students, function($a, $b) {
    return $a['score'] <=> $b['score'];
});

The above code will sort the array from small to large student scores:

[
    ['name' => 'Carol', 'score' => 80],
    ['name' => 'Alice', 'score' => 85],
    ['name' => 'Bob', 'score' => 90],
];

The above is the detailed content of Advanced sorting of PHP arrays: custom comparators and anonymous functions. For more information, please follow other related articles on the PHP Chinese website!