PHP 8 reference · String Functions

PHP strtoupper() Function

Convert every ASCII letter in a string to uppercase. Letters such as é stay unchanged; use mb_strtoupper() for those.

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Syntax

strtoupper(string $string): string

Parameter	Description
`string`	The input string.

The uppercased string.

Uppercase textTry it yourself

<?php
echo strtoupper("camel case"), "\n";
echo strtoupper("order #a12-b"), "\n"; // digits and symbols stay

Output

CAMEL CASE
ORDER #A12-B

Accented letters need mb_strtoupper()Try it yourself

<?php
echo strtoupper("café"), "\n";
echo mb_strtoupper("café"), "\n";

Output

CAFé
CAFÉ

Version	Change
PHP 4.0	Added
PHP 8.2	Case conversion no longer depends on the locale: only ASCII letters a–z change.

strtolower() · Convert every ASCII letter in a string to lowercase. Since PHP 8.2 it ignores the locale; use mb_strtolower() for é, Ü and others.
mb_strtoupper() · Convert a string to uppercase, including letters outside ASCII such as é, ß and Cyrillic. The Unicode-aware strtoupper().
ucwords() · Uppercase the first letter of each word in a string. By default words are separated by spaces, tabs and new lines.
PHP Strings · tutorial