How to modify the key value of an array in PHP

In PHP, array is a very commonly used data type, which allows us to store and operate a set of ordered and unordered data. However, sometimes we need to modify the key values ​​in the array to achieve better data operation and management. This article will introduce how to modify the key value of an array in PHP.

1. PHP Array Basics

In PHP, an array is an ordered associative data type. It consists of key-value pairs, where each key represents an identifier and the corresponding value represents the data corresponding to the identifier. The key of a PHP array can be any string or number, and the value can be any PHP data type.

The following is a simple PHP array example:

$fruits = array(
    "apple" => 1,
    "banana" => 2,
    "orange" => 3
);

In the above example, $fruits is an array variable, which contains three key-value pairs, That is, "apple" => 1, "banana" => 2 and "orange" => 3. Here, "apple", "banana" and "orange" are key values, which represent the name of the fruit, and 1, 2 and 3 are the corresponding values, representing the quantity of each fruit.

2. Modification of key in PHP array

Although the key value in PHP array is immutable, sometimes we need to modify it to achieve better data operation and management . So, how to modify the array key value in PHP?

PHP provides some built-in functions to accomplish this task. Two common methods are introduced below:

1. Use the array_combine function

array_combineThe function can convert two arrays into a new array. The value of one array will become the key of the new array, and the value of the other array will become the value of the new array. We can use this function to modify the key value in the PHP array.

For example, suppose we have an array:

$fruits = array(
    "apple" => 1,
    "banana" => 2,
    "orange" => 3
);

Now, we want to change the value of "banana" to "pear", then This can be done using the following code:

$new_key = "pear";
$new_fruits = array_combine(
    array_replace(array_keys($fruits), array_fill(array_search("banana", $fruits), 1, $new_key)), 
    $fruits
);

print_r($new_fruits);

In the above code, we use the array_keys function to obtain all key values ​​​​of the original array, and use the array_replace function to "banana" is replaced with "pear". Finally, we combine the modified key array and the original array into a new array, thus obtaining the modified array.

2. Use the array_splice function

Another way to modify the key value in a PHP array is to use the array_splice function. This function can insert or delete elements from the middle of the array and return the deleted element. We can use this function to modify the key value in the PHP array.

For example, suppose we have an array:

$fruits = array(
    "apple" => 1,
    "banana" => 2,
    "orange" => 3
);

Now, we want to change the key value of "banana" to "pear", Then you can use the following code to complete:

$new_key = "pear";
$value = $fruits["banana"];
array_splice($fruits, array_search("banana", array_keys($fruits)), 1, array($new_key => $value));

print_r($fruits);

In the above code, we use the array_search function to obtain the key value of "banana" in the original array, and use array_splice function deletes it. Then, we create a new array with the key and value values ​​​​"pear" and 2, and use the array_splice function to insert it into the original array The position where "banana" is deleted. Finally, we get the modified array.

3. Summary

In PHP, array is a very commonly used data type, which consists of some key-value pairs. Although key values ​​in PHP arrays are immutable, sometimes we need to modify them for better data manipulation and management. This article introduces two common methods of modifying keys in PHP arrays, and also provides sample code. I hope it will be helpful to everyone who encounters problems in PHP array operations.

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