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<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <title>PHP Convert Array Keys to Uppercase</title> </head> <body> <pre> <?php // Sample array $persons = array("Harry"=>22, "Clark"=>32, "John"=>28); // Changing keys to uppercase print_r(array_change_key_case($persons, CASE_UPPER)); ?> </pre> </body> </html>
