How to convert array key names to uppercase using PHP

As a popular programming language, PHP has powerful array processing functions. When processing arrays, sometimes you need to perform some operations on the array key names, such as converting the array key names to uppercase. This article will introduce how to use PHP to convert array key names to uppercase.

Method 1: Use array_change_key_case() function

PHP provides an array_change_key_case() function for converting array key names to uppercase and lowercase. This function has two parameters. The first parameter is the array that requires key name operation, and the second parameter specifies the case type of conversion (the optional value is CASE_LOWER or CASE_UPPER).

The following is an example of converting the array key name to uppercase:

$myArray = array("name" => "John", "age" => 30);
$myArray = array_change_key_case($myArray, CASE_UPPER);
print_r($myArray);

Execute the above code, the output result is as follows:

Array
(
    [NAME] => John
    [AGE] => 30
)

Method 2: Use array_combine() function

Another method is to use the array_combine() function. This function merges two arrays into a new array, where the key name of one array will be used as the key name of the new array, and the value of the other array will be used as the value of the new array. Therefore, you can use an array containing uppercase key names as the key array, and then use the original array as the value array to generate a new array.

The following is an example of using the array_combine() function to convert the array key name to uppercase:

$myArray = array("name" => "John", "age" => 30);
$uppercaseKeys = array_map('strtoupper', array_keys($myArray));
$newArray = array_combine($uppercaseKeys, $myArray);
print_r($newArray);

Execute the above code, the output result is as follows:

Array
(
    [NAME] => John
    [AGE] => 30
)

Method 3: Use array_map() function

Another method is to use the array_map() function to operate on the key names of the array. This function applies a callback function to each element of the array, where the strtoupper() function is used to convert the key name to uppercase. Finally a new array is generated.

The following is an example of using the array_map() function to convert array key names to uppercase:

$myArray = array("name" => "John", "age" => 30);
$newArray = array_combine(array_map('strtoupper', array_keys($myArray)), $myArray);
print_r($newArray);

Execute the above code, the output results are as follows:

Array
(
    [NAME] => John
    [AGE] => 30
)

Summary

This article introduces three methods of converting PHP array key names to uppercase: using the array_change_key_case() function, using the array_combine() function, and using the array_map() function. These techniques are easy to use and can improve the efficiency of PHP array processing. If you have similar needs, you can choose a method that suits you according to your needs.

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