How to convert English lowercase characters to uppercase characters in php

In web development, converting strings into uppercase or lowercase is a very common operation. When we need to convert English lowercase characters to uppercase, PHP provides several methods to choose from. In this article, we will introduce how to convert English lowercase characters to uppercase characters.

Method 1: strtoupper() function

The strtoupper() function in PHP is one of the basic functions that converts all lowercase letters in a string into uppercase letters.

The following is an example:

$str = "hello world";
echo strtoupper($str);

The output result is:

HELLO WORLD

Method 2: mb_strtoupper() function

In some cases, if the character If the string contains non-ASCII characters (such as Unicode characters), problems may occur when using the strtoupper() function. At this time, we can use PHP's mb_strtoupper() function to solve the problem.

The following is an example:

$str = "你好，世界！";
echo mb_strtoupper($str, 'UTF-8');

The output result is:

你好，世界！

Method 3: Use the ctype_upper() function

ctype_upper() function is used Checks whether a string contains all uppercase letters.

The following is an example:

$str = "HELLO WORLD";
if (ctype_upper($str)) {
    echo "字符串全为大写字母";
}

The output result is:

字符串全为大写字母

Method 4: Manual conversion

Of course, we can also manually convert the string into Convert lowercase letters to uppercase letters.

The following is an example:

$str = "hello world";
for ($i=0; $i<strlen>= 97 && ord($str[$i]) <p>The output is: </p>
<pre class="brush:php;toolbar:false">HELLO WORLD

The above are four common methods for converting English lowercase characters into uppercase characters. Choosing the appropriate method according to the actual situation can effectively improve development efficiency.

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