How to merge several arrays in php

In PHP, array is a very common and important data type, and it is often necessary to merge several arrays into one. This article will use examples to introduce in detail several methods of merging multiple arrays in PHP.

Method 1: Use the " " operator

You can use the " " operator to combine two arrays and retain the values ​​of elements with duplicate key names. If the key name is repeated, the elements in the first array will be retained. For example:

$array1 = array("a"=>"red", "b"=>"green");
$array2 = array("c"=>"blue", "b"=>"yellow");
$result = $array1 + $array2;
print_r($result);

The output is:

Array
(
    [a] => red
    [b] => green
    [c] => blue
)

Method 2: Use the array_merge() function

array_merge() function to merge two or more arrays into one array, no Keep the values ​​of elements with duplicate keys. For example:

$array1 = array("a"=>"red", "b"=>"green");
$array2 = array("c"=>"blue", "b"=>"yellow");
$result = array_merge($array1, $array2);
print_r($result);

The output is:

Array
(
    [a] => red
    [b] => yellow
    [c] => blue
)

If the merged array has the same key name, the value corresponding to the key name in the merged array will be the value corresponding to the key name in the subsequent array value.

Method 3: Use array_replace() function

array_replace() function will replace the elements with the same key name in the first array and the second array, and use the second Replace the element in the first array with the element corresponding to the key in the array. For example:

$array1 = array("a"=>"red", "b"=>"green");
$array2 = array("b"=>"blue", "c"=>"yellow");
$result = array_replace($array1, $array2);
print_r($result);

The output is:

Array
(
    [a] => red
    [b] => blue
    [c] => yellow
)

If the key name in the first array does not exist in the second array, the key name will not be replaced.

Method 4: Use the array_combine() function

The array_combine() function uses the key name in one array as the value in another array and merges the two arrays into a new array. For example:

$array1 = array("a", "b", "c");
$array2 = array("red", "green", "blue");
$result = array_combine($array1, $array2);
print_r($result);

The output is:

Array
(
    [a] => red
    [b] => green
    [c] => blue
)

If the two arrays are of different lengths, an error will be thrown.

Method 5: Use the "[]" operator

Starting from PHP5.4 version, you can use the "[]" operator to merge two arrays into one array. For example:

$array1 = array("a"=>"red", "b"=>"green");
$array2 = array("c"=>"blue", "b"=>"yellow");
$result = $array1 + $array2;
print_r($result);

The output is:

Array
(
    [a] => red
    [b] => green
    [c] => blue
)

The result is the same as using the " " operator.

The above five methods can combine two or more arrays into one. Which method to use specifically depends on the actual situation and needs to choose the most appropriate method.

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