Learn array_change_key_case php function in 1 minute

Function name:  array_change_key_case php function.

There are few things which you need to keep in mind before start to understand this tutorial. You should have basic understanding of php arrays, print_r function & foreach

Syntax: array_change_key_case(array, case)
Support: PHP (4>=4.2.0, 5, 7)
Return Type: array_change_key_case php function will always return array.


  • array(neccessary)
  • case(optional)

Description about array_change_key_case php function:

With the help of this function we can change the keys case to upper or lower.

Array: It’s collection of information on which we want to perform our action like changing the keys case.
Case: It’s just a case defined my php, there are only two options available CASE_UPPER, CASE_LOWER. By default, CASE_LOWER is already set.

Tip: array_change_key_case php function, only works on associative array.But, also will not generate errors, if you’ll pass out indexed or integer array.

Example 1:
In this example, we have an array of header_title that contains some information about fictional company. This example will show you, what happens when we don’t put any case.

//When we don't put the case, CASE_UPPER OR CASE_LOWER
$header_title = array('company name' => 'XicTech',  'Service'=>'SEO | Digital marketing | Web Designing');

Array (
[company name] => XicTech
[service] => SEO | Digital marketing | Web Designing

The keys are now in lower case right? As I told you, by default case is CASE_LOWER

Example 2:
I am taking same example as above but by passing second parameter case as CASE_UPPER. It’s really simple, what it will do? Let’s check that out.

//When we are putting CASE_UPPER 

$header_title = array('company name' => 'XicTech',  'Service'=>'SEO | Digital marketing | Web Designing');

print_r(array_change_key_case($header_title, CASE_UPPER));

Array (
[SERVICE] => SEO | Digital marketing | Web Designing

The keys are now in upper case, because we used CASE_UPPER.

Now, the question is how we can use array_change_key_case php function in real world. Let’s do some basic example.

Example 3:
In this example, I have same array as we wrote. That was header_title, but the only difference is I am doing some extra work here like storing header_title upper case version in another array that is header_info.

$header_title = array('company name' => 'XicTech',  'Service'=>'SEO | Digital marketing | Web Designing');
$header_info=array_change_key_case($header_title, CASE_UPPER);

foreach($header_info as $key => $value){
    echo($key." : ". $value . "<br/>");

SERVICE : SEO | Digital marketing | Web Designing

We displayed the keys in upper case to show the impact of titles (COMPANY NAME & SERVICE).

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