How to merge arrays in php? Brief analysis of three methods

In PHP programming, it is often necessary to merge two or more arrays into one array, which requires the use of the merge array function provided by PHP. PHP provides three different functions to merge arrays. Let's take a look at the usage of these three functions.

1. Use array_merge() function to merge arrays
array_merge() function can merge two or more arrays. The syntax format is as follows:

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

Among them, array1 is the first array to be merged. An array, followed by optional parameters, representing other arrays to be merged.

It should be noted that array_merge() will reset the key names of the original array, and key values ​​with the same key names will be overwritten by subsequent ones, for example:

$a = array("a" => "apple", "b" => "banana");
$b = array("a" => "pear");
$result = array_merge($a, $b);

print_r($result);

/*
输出结果：
Array ( [a] => pear [b] => banana )
*/

2. Use array_replace () Function to merge arrays
array_replace() function can also merge two or more arrays. The syntax format is as follows:

array array_replace ( array $array1, array $array2 [, array $... ] )

Among them, array1 is the first array to be merged, array2 and the following can The optional parameters represent other arrays to be merged.

It should be noted that array_replace() will replace the corresponding value of the previous array with the value of the subsequent array, for example:

$a = array("a" => "apple", "b" => "banana");
$b = array("a" => "pear");
$result = array_replace($a, $b);

print_r($result);

/*
输出结果：
Array ( [a] => pear [b] => banana )
*/

3. Use the " " operator to merge arrays
Except For the above two functions, there is a simpler way, which is to use the " " operator to merge arrays. This method will merge the previous array and the following array into a new array, and retain the key values ​​​​of the original array, for example:

$a = array("a" => "apple", "b" => "banana");
$b = array("a" => "pear");
$result = $a + $b;

print_r($result);

/*
输出结果：
Array ( [a] => apple [b] => banana )
*/

It should be noted that if the two arrays have the same key name , then the " " operator will select the key value corresponding to the previous array, and the key value corresponding to the subsequent array will be ignored.

To sum up, the above three methods can all merge PHP arrays. We can choose different methods according to actual needs.

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