How to convert letters to uppercase in PHP

PHP is a widely used scripting language, often used in web development, server-side scripting and other fields. In PHP, there are many built-in functions that make it easy to perform various common operations, including converting letters to uppercase. This article will introduce how to convert letters to uppercase in PHP and explore how to apply it in actual development.

1. Use the strtoupper function to convert letters to uppercase

In PHP, use the strtoupper function to convert all letters in a string to uppercase. The syntax format is as follows:

strtoupper(string $str): string

This function accepts a string as a parameter, converts all its letters to uppercase, and returns the converted string.

The following is a simple sample code:

$str = "hello world";
$str = strtoupper($str);
echo $str; // 输出HELLO WORLD

2. Use the ucwords function to convert the first letter of each word to uppercase

Different from the strtoupper function, the ucwords function can The first letter of each word is converted to uppercase. Its syntax is as follows:

ucwords(string $str): string

This function accepts a string as a parameter and splits it into words, then converts the first letter of each word to uppercase and returns the converted string.

The following is a simple sample code:

$str = "hello world";
$str = ucwords($str);
echo $str; // 输出Hello World

3. Use the mb_strtoupper function to convert multi-byte strings to uppercase

In some cases, the string contains The characters may be multibyte characters. At this time, using the strtoupper function and the ucwords function does not correctly convert it to uppercase. PHP provides a mb_strtoupper function that can solve this problem. The syntax format of this function is as follows:

mb_strtoupper(string $str [, string $encoding = mb_internal_encoding()]): string

This function accepts a string as a parameter, converts all its characters to uppercase, and returns the converted string. The optional second parameter encoding specifies the encoding method of the string, which defaults to the internal encoding method.

The following is a simple sample code:

$str = "こんにちは世界";
$str = mb_strtoupper($str, 'UTF-8');
echo $str; // 输出こんにちは世界

4. Summary

In PHP, converting letters to uppercase is very simple. You can use the strtoupper function to convert the entire string to uppercase, or you can use the ucwords function to convert the first letter of each word to uppercase. For multi-byte strings, you can use the mb_strtoupper function. In the actual development process, we can choose different functions to implement letter case conversion according to needs.

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