array_change_key_case

Definition and usage

array_change_key_case() function converts all keys of an array into uppercase or lowercase letters.

The numeric index of the array does not change. If no optional parameter is provided (i.e. the second parameter), the default conversion is to lowercase letters.

Example

Example 1

Convert all keys of the array to capital letters:

 <?php
$age = array ( "Bill" => "60" , "Steve" => "56" , "Mark" => "31" ) ;
print_r ( array_change_key_case ( $age , CASE_UPPER ) ) ;
?>

Try it yourself

Example 2

Convert all keys of the array to lowercase letters:

 <?php
$age = array ( "Bill" => "60" , "Steve" => "56" , "Mark" => "31" ) ;
print_r ( array_change_key_case ( $age , CASE_LOWER ) ) ;
?>

Try it yourself

Example 3

If two or more keys are equal after running array_change_key_case() (such as "b" and "B"), the last element overwrites the other elements:

 <?php
$pets = array ( "a" => "Cat" , "B" => "Dog" , "c" => "Horse" , "b" => "Bird" ) ;
print_r ( array_change_key_case ( $pets , CASE_UPPER ) ) ;
?>

Try it yourself

grammar

 array_change_key_case ( array , case ) ;