PHP strtoupper() Function

In this tutorial, we'll explore how to use the strtoupper() function in PHP to convert an input string to upper case.
Captain Salem 2 min read
PHP strtoupper() Function

Case conversion is one of the most popular string operations used in programming and text processing. It refers to the process of changing the case of characters in a string, such as converting all characters to uppercase or lowercase.

This operation is particularly useful when dealing with strings that have inconsistent or mixed cases, as it allows you to standardize the text and make it easier to work with.

PHP strtoupper() Function

As the name probably suggests, this function allows us to convert a string to uppercase. The function syntax is as demonstrated below:

strtoupper(string $string): string

The function accepts only one parameter:

  1. string - refers to input string whose casing you wish to convert to uppercase.

The function will then return the uppercased string.

NOTE: The function will return the string with all the ASCII alphabetic characters converted to uppercase. Hence, the function will ignore multibyte UTF-8 encoded characters.


The following code snippet demonstrates how we can use the strtoupper() function to convert a string to uppercase in PHP.

$string = "Hello, World!";
$uppercase = strtoupper($string);
echo $uppercase;

The resulting output is as shown:


Common Use cases

The strtoupper() function in PHP is commonly used in various applications, such as:

  1. Formatting User Input - The strtoupper() function is useful in formatting user input data, particularly when the data entered by the user may be in mixed or inconsistent case. This ensures that the data is standardized and easier to process.
  2. Comparing Strings - The strtoupper() function can be used to standardize the case of strings for comparison purposes. For example, when comparing two strings, converting both strings to uppercase ensures that they have the same case and eliminates the possibility of case sensitivity causing discrepancies.
  3. Sorting Data - The strtoupper() function is also useful in sorting data, particularly when sorting strings alphabetically. Converting all strings to uppercase ensures that they are sorted in a consistent manner, regardless of the original case of the text.
  4. Database Operations - The strtoupper() function is often used in database operations, particularly when searching for records in a case-insensitive manner. By converting both the search term and the database records to uppercase, the search results will include records regardless of their original case.


In this tutorial, we discussed how to use the strtoupper() function to convert an input string to uppercase.

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