Detailed explanation of the usage of PHP's array_merge_recursive () function

PHP is a widely used open source server-side scripting language. If you are a beginner of PHP, you may have already understood the basic syntax of using arrays. In many cases, it is very necessary to process arrays and merge them, which is why PHP provides an array_merge_recursive() function.

The array_merge_recursive() function is one of PHP's built-in functions, which is used to merge one or more arrays. This function will merge the elements of all arrays, including nested arrays. This function behaves slightly differently when merging two or more arrays with each other. This article will introduce you to the detailed usage of the array_merge_recursive() function in PHP.

Basic usage

The basic syntax of the array_merge_recursive() function is as follows:

array array_merge_recursive(array $array1 [, array $... ])

The $array1 parameter is the first array to be merged, and the $... parameter is The other arrays to be merged can be any number of arrays. This function returns the combined result of multiple arrays. The following is a simple example:

$array1 = array('a' => array('b', 'c'));
$array2 = array('a' => array('d', 'e'));

$result = array_merge_recursive($array1, $array2);
print_r($result);

The output result is as follows:

Array
(
    [a] => Array
        (
            [0] => b
            [1] => c
            [2] => d
            [3] => e
        )
)

As you can see, when we merge the arrays $array1 and $array2, the array 'b' under 'a', 'c' is merged into the result, and the arrays 'd' and 'e' under 'a' are also merged into the result.

Processing of array key names

When using the array_merge_recursive() function, if the arrays to be merged have the same string key names, the elements of these arrays will be merged into one array.

$array1 = array('a' => 'apple', 'b' => 'banana');
$array2 = array('a' => 'pear', 'c' => 'cherry');

$result = array_merge_recursive($array1, $array2);
print_r($result);

The output of the above code is as follows:

Array
(
    [a] => Array
        (
            [0] => apple
            [1] => pear
        )
    [b] => banana
    [c] => cherry
)

As you can see, since the arrays $array1 and $array2 both have the key name 'a', in the result, under 'a' The array contains their values.

Merging of nested arrays

The array_merge_recursive() function can correctly handle the merging of nested arrays. When the array elements to be merged are arrays, this function will recursively merge the arrays. For example:

$array1 = array('a' => array('b', 'c'));
$array2 = array('a' => array('d', 'e'));

$result = array_merge_recursive($array1, $array2);
print_r($result);

The output of the above code is as follows:

Array
(
    [a] => Array
        (
            [0] => b
            [1] => c
            [2] => d
            [3] => e
        )
)

You can see that when merging arrays $array1 and $array2, both arrays contain a key 'a' and an array , at this time array_merge_recursive() will recursively merge the two arrays and merge them into a new array under key 'a'.

Merge of objects

The array_merge_recursive() function can also be used to merge objects. When merging objects, this function will prefer merging properties of those objects rather than object instances.

class Fruit {
    public $name;
    public $color;

    public function __construct($name, $color) {
        $this->name = $name;
        $this->color = $color;
    }
}

$apple = new Fruit('apple', 'red');
$banana = new Fruit('banana', 'yellow');
$pear = new Fruit('pear', 'green');

$result = array_merge_recursive((array)$apple, (array)$banana, (array)$pear);
print_r($result);

The above code will create three different Fruit objects and convert them to arrays, then merge them using the array_merge_recursive() function.

The output results are as follows:

Array
(
    [name] => Array
        (
            [0] => apple
            [1] => banana
            [2] => pear
        )
    [color] => Array
        (
            [0] => red
            [1] => yellow
            [2] => green
        )
)

You can see that in the result array, the properties of all objects are merged into arrays.

Summary

The array_merge_recursive() function is a widely used function in PHP. It can be used to merge one or more arrays, including nested arrays and objects. The biggest feature of this function is that it can merge nested arrays recursively. When using this function, you need to pay attention to the handling of array key names to avoid unnecessary errors. Remember to use this function as needed during actual development to avoid excessive merging operations that affect code execution efficiency.

The above is the detailed content of Detailed explanation of the usage of PHP's array_merge_recursive () function. For more information, please follow other related articles on the PHP Chinese website!