How to convert array subscripts to lowercase in php

In PHP programming, arrays are a very common data type. In some cases, we need to convert all subscripts in the array to lowercase. This operation can be done easily and only requires a few lines of code.

The following will introduce how to convert array subscripts into lowercase in PHP.

1. Use the array_change_key_case() function

PHP provides an array_change_key_case() function, which can convert all subscripts in the array into uppercase or lowercase. The syntax of this function is as follows:

array array_change_key_case(array $array, int $case = CASE_LOWER)

Among them, $array is the array to be converted, $case is an optional parameter, indicating conversion into uppercase or lowercase. When $case is 0 (default value), it means converting to lowercase; when $case is 1, it means converting to uppercase.

The following is an example of using the array_change_key_case() function:

$old_array = array(

'aBc' => 'Hello',
'def' => 'world',
'GHI' => '!'

);

$new_array = array_change_key_case($old_array, CASE_LOWER);

print_r($new_array);
?>

The output of this code is:

Array
(

[abc] => Hello
[def] => world
[ghi] => !

)

You can see that aBc, def, and GHI in the original array have been converted to lowercase.

2. Use foreach loop

In addition to using the array_change_key_case() function, we can also use the foreach loop to traverse the array and convert each subscript into lowercase. Here is a sample code:

$old_array = array(

'aBc' => 'Hello',
'def' => 'world',
'GHI' => '!'

);

$new_array = array();
foreach ($old_array as $key => $value) {

$new_key = strtolower($key);
$new_array[$new_key] = $value;

}

print_r($new_array);
?>

The output of this code The result is the same as the sample code above.

3. Notes

When converting array subscripts into lowercase, you need to pay attention to some details. For example:

• If there are multiple subscripts with the same subscript (but different cases) in the original array, they will be merged into one item after conversion;
• If there are numbers in the original array as subscripts The subscript will not be affected after conversion, and the numerical subscript is still a number;
• The order of the elements of the converted array is not necessarily the same as that of the original array.

To sum up, converting array subscripts to lowercase in PHP is a relatively simple matter. This can be achieved using the array_change_key_case() function or foreach loop. No matter which method is used, there are some details that need to be paid attention to to ensure that the results are as expected.

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