Introduction to how to use the array_merge_recursive() function in the PHP function library

The array_merge_recursive() function is one of the commonly used functions in PHP, which is used to merge one or more arrays. Unlike the array_merge() function, the array_merge_recursive() function can handle multi-dimensional arrays. This means that when multiple multidimensional arrays need to be merged, the array_merge_recursive() function will merge the values ​​of duplicate key names into one array.

Let’s introduce in detail how to use the array_merge_recursive() function.

1. Function syntax

array_merge_recursive(array1, array2, array3, …)

2. Parameter description

array1 is one of the arrays to be merged , required parameters;

array2, array3,...are other arrays to be merged, optional parameters.

3. Return value

array_merge_recursive() function returns a merged array. If a duplicate key name appears during the merge process, the values ​​under the key name will be merged into an array.

4. Usage example

The following demonstrates a simple usage example of the array_merge_recursive() function:

array1 = array('name'=>'PHP', ' version' => '7.2');
array2 = array('name'=>'MySQL', 'version' => '5.7', 'extension'=>array('pdo', ' mysqli'));
$array3 = array('name'=>'HTML', 'version' => '5', 'extension'=>array('canvas', 'video')) ;

$arr ​​= array_merge_recursive($array1, $array2, $array3);

print_r($arr);

After executing the above code, the output result is:

Array
(

[name] => Array
    (
        [0] => PHP
        [1] => MySQL
        [2] => HTML
    )

[version] => Array
    (
        [0] => 7.2
        [1] => 5.7
        [2] => 5
    )

[extension] => Array
    (
        [0] => pdo
        [1] => mysqli
        [2] => canvas
        [3] => video
    )

)

As can be seen from the output results, the values ​​under the repeated "name" and "version" key names in the merged array merged into arrays.

5. Notes

When using the array_merge_recursive() function, you need to pay attention to the following points:

(1) The order of array merging will affect the key name of the merged array value.

(2) If the value is not an array, it will be forced to be converted to an array type, so the return value of the function is always an array type.

(3) When another array appears in the merged array, the sub-array will be recursed and the elements in it will be merged.

(4) This function does not break up the string, so the string will not be split into a single character array.

Summary:

The array_merge_recursive() function is a commonly used array merging function in PHP and is suitable for merging multi-dimensional arrays. This function is affected by the order of the array, and the values ​​under the merged array key names are affected. You need to pay attention to the above details when using it to avoid unexpected merge results. I hope the introduction of this function will be helpful to everyone.

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