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In PHP, the operation of arrays is a very common task, especially when it is necessary to reorganize arrays based on certain conditions. The array_combine function is a very useful tool provided by PHP, which allows you to generate a new associative array based on two arrays. Specifically, array_combine creates a new associative array by taking the first array as the key and the second array as the value.
The basic syntax of the array_combine function is as follows:
array_combine(array $keys, array $values): array|false
$keys : an array that will be used as the new array key.
$values : an array that will be used as the new array value.
This function takes each element in the $keys array as the key to the new array and each element in the $values array as the value of the new array. If the number of elements of the two arrays is different, it will return false .
Let's look at a simple example, suppose we have two arrays: one is an array containing the names of fruits, and the other is an array of price of these fruits. We want to combine these two arrays into an associative array, the key is the name of the fruit and the value is the price of the fruit.
<?php
// Define fruit name array
$fruits = ['apple', 'banana', 'orange'];
// Define fruit price array
$prices = [1.2, 0.5, 0.8];
// use array_combine Merge these two arrays
$fruitPrices = array_combine($fruits, $prices);
// Print results
print_r($fruitPrices);
?>
Output result:
Array
(
[apple] => 1.2
[banana] => 0.5
[orange] => 0.8
)
In this example, we successfully used the fruit name as the key and the fruit price as the value to generate a new associative array.
The array length is the same : array_combine requires that the lengths of the two arrays must be the same. If they are different in length, the function returns false .
Example:
$keys = ['a', 'b', 'c'];
$values = [1, 2];
$result = array_combine($keys, $values); // return false，Because the array length is different
Key names cannot be repeated : If there are duplicate elements in the $keys array, array_combine will be assigned according to the last key value that appears, and the previous key value will be overwritten.
Example:
$keys = ['a', 'b', 'a'];
$values = [1, 2, 3];
$result = array_combine($keys, $values); // return ['a' => 3, 'b' => 2]
array_combine is suitable for the following common scenarios:
Data format conversion : Convert index arrays to associative arrays. For example, you have a set of data that you want to organize according to certain key values.
For example, suppose you query an array of user information from the database and you want to use each field name as the key to the array:
$keys = ['name', 'age', 'email'];
$values = ['John Doe', 25, 'john@example.com'];
$user = array_combine($keys, $values);
print_r($user);
Output:
Array
(
[name] => John Doe
[age] => 25
[email] => john@example.com
)
Remap array : Suppose you have an old set of data structures that you want to remap into a new structure through array_combine , so that subsequent processing is more convenient.
If the array length passed in does not match when using array_combine , the function returns false . In order to avoid errors, you can judge the return value by if and do the corresponding error handling:
<?php
$keys = ['id', 'name'];
$values = [101];
$result = array_combine($keys, $values);
if ($result === false) {
echo "Array length mismatch，Unable to merge！";
} else {
print_r($result);
}
?>
array_combine is a very powerful function, especially suitable for combining two arrays into an associative array. Its usage is simple and direct, but it should be noted that the lengths of the two arrays must be the same, otherwise false will be returned. By using this function reasonably, we can more conveniently reconstruct the array mapping and improve development efficiency.
Related articles <br> For more information about PHP array operations, please refer to the following link:
PHP array_combine function documentation
PHP array function collection
