PHP strtoupper Function

Summary: in this tutorial, you’ll learn how to use the PHP strtoupper() function to convert all alphabetic characters of a string to uppercase.

Introduction to the PHP strtoupper() function

The strtoupper() function accepts a string and returns a new string with all alphabetic characters converted to uppercase.

The following shows the syntax of the strtoupper() function:

strtoupper ( string $string ) : stringCode language: PHP (php)

The strtoupper() uses the current locale to determine alphabetic characters.

To return a new string in a specific encoding with all alphabetic characters converted to uppercase, you use the mb_strtoupper() function instead:

mb_strtoupper ( string $string , string|null $encoding = null ) : stringCode language: PHP (php)

The following defines a upper() function that returns a new string with all characters converted uppercase:

<?php

if (!function_exists('upper')) {
    function upper(string $value) : string
    {
        return mb_strtoupper($value, 'UTF-8');
    }
}Code language: PHP (php)

To return a new string with all alphabetic characters converted to lowercase, you use the strtolower() function.

PHP strtoupper() function examples

The following example uses the strtoupper() function to convert the string php to uppercase:

<?php

echo strtoupper('php');Code language: PHP (php)

Output:

PHPCode language: PHP (php)

Summary

Use the strtoupper() function to return a new string from a string with all characters converted to uppercase.
Use the mb_strtoupper() to convert a string with a specific encoding to uppercase.

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