How to convert string to uppercase in PHP-PHP Tutorial-php.cn

php editor Banana today will introduce to you how to convert a string into uppercase. In PHP, you can use the built-in function strtoupper() to achieve this function, which converts all letters in the string to uppercase. This function is very practical, especially suitable for scenarios that require a unified string format. Next, we will explain in detail how to use the strtoupper() function to convert a string into uppercase, so that you can easily master this skill during development.

phpConvert string to uppercase

In PHP, converting a string to uppercase is a common operation. This article will introduce several methods in detail to help you easily convert strings to uppercase.

Method 1: strtoupper() function

This is the most common method, just pass the string as a parameter to thestrtoupper()function.

$str = "hello world"; $upperCaseStr = strtoupper($str); echo $upperCaseStr; // Output: HELLO WORLD

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Method 2: mb_strtoupper() function

This function is the multibyte version of thestrtoupper()function, suitable for non-ASCII character sets.

$str = "Hello world"; $upperCaseStr = mb_strtoupper($str); echo $upperCaseStr; // Output: Hello world (uppercase)

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Method 3: Use built-in constants

PHP provides the built-in constantSTR_TO_UPPER, which can be used to convert a string to uppercase.

$str = "hello world"; $upperCaseStr = strtr($str, "abcdefghijklmnopqrstuvwxyz", "ABCDEFGHIJKLMNOPQRSTUVWXYZ"); echo $upperCaseStr; // Output: HELLO WORLD

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Method 4: Use`preg_replace()`function

preg_replace()The function can be used to replace lowercase characters in a string with uppercase characters usingregular expressions.

$str = "hello world"; $upperCaseStr = preg_replace("/[a-z]/", strtoupper("$0"), $str); echo $upperCaseStr; // Output: HELLO WORLD

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Method 5: Use`array_map()`function

array_map()The function can be used to convert each element in anarrayto uppercase.

$str = "hello world"; $strArr = str_split($str); $upperCaseArr = array_map("strtoupper", $strArr); $upperCaseStr = implode("", $upperCaseArr); echo $upperCaseStr; // Output: HELLO WORLD

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Summarize

The above methods can effectively convert PHP strings to uppercase. Which method you choose depends on your string's special requirements and performance considerations.

method	Advantage	Disadvantages
`strtoupper()`	Easy to use	Non-ASCII character sets are not supported
`mb_strtoupper()`	Support multi-byte character sets	Slower than`strtoupper()`
Built-in constants	Reliable and efficient	Multi-byte character sets are not supported
`preg_replace()`	Flexible and powerful	The performance overhead is higher than other methods
`array_map()`	Applies to string arrays	Requires string splitting and reassembly

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