Preliminary PHP function: array_merge()

PHP is an open source scripting language that is welcomed and used by programmers around the world. PHP is very powerful and provides many practical functions when processing arrays, such as the array_merge() function.

The array_merge() function can merge one or more arrays into one array. Let's take a look at the usage and precautions of this function.

Syntax:

array_merge ( array $array1 [, array $... ] ) : array

Parameters:

• array1: Required. The first array to be merged.
• ...: Optional. There can be multiple other arrays to be merged.

Return value:

• Returns the merged array. If any input array is an empty array, the function returns an empty array.

Example 1:

$array1 = array('a'=>1,'b'=>2,'c'=>3);
$array2 = array('d'=>4,'e'=>5,'f'=>6);
$result_array = array_merge($array1,$array2);
print_r($result_array);

Output:

Array
(
    [a] => 1
    [b] => 2
    [c] => 3
    [d] => 4
    [e] => 5
    [f] => 6
)

Example 2:

$array1 = array('a'=>1,'b'=>2,'c'=>3);
$array2 = array('d'=>4,'e'=>5,'f'=>6);
$array3 = array('g'=>7,'h'=>8,'i'=>9);
$result_array = array_merge($array1,$array2,$array3);
print_r($result_array);

Output:

Array
(
    [a] => 1
    [b] => 2
    [c] => 3
    [d] => 4
    [e] => 5
    [f] => 6
    [g] => 7
    [h] => 8
    [i] => 9
)

Notes:

• The array_merge() function can only merge array type variables, and other types of variables will be converted to array types. For example, if a variable of type string is merged, the program will convert it into an array containing the string.
• If two or more arrays contain elements with the same key name, the subsequent elements will overwrite the original elements. Therefore, subsequent elements will overwrite the original elements.
• If a key name is an integer, it will be converted to a string type.
• If there are no input parameters, an empty array is returned.
• If there is only one parameter and the parameter is an array, the function will return the original array without performing any operation.

Summary:

The array_merge() function is a very practical function in PHP array operations. It has a wide range of uses and can easily merge multiple arrays into one array. However, when using this function, you need to pay attention to the above points to avoid errors.

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