How to validate Chinese character input using PHP regular expressions

With the popularization of the Internet and the advancement of internationalization, more and more users come from various countries and regions, and the usage of Chinese character input in user input has also increased. The verification of Chinese characters is an important part for some Chinese websites or international websites. For developers, it is very necessary to understand how to use PHP regular expressions to verify Chinese character input.

PHP is a commonly used server programming language. It is favored by many developers for its simplicity, ease of learning, openness and freedom. Regular expressions are a powerful tool for processing text. They are highly portable and can be used in different programming languages. Therefore, it is very practical to verify Chinese character input through PHP regular expressions.

Next, I will introduce how to use PHP regular expressions to verify Chinese character input, and how to deal with some special situations that may occur in Chinese character input.

1. PHP regular expression verification of Chinese character input

In PHP, use the preg_match() function to match regular expressions. The syntax format is as follows:

preg_match( string $pattern , string $subject [, array &$matches [, int $flags = 0 [, int $offset = 0 ]]]): int|false

Among them, $pattern is the regular expression pattern to be matched, $subject is the string to be matched, and $matches is used to store the matching results. If the match is successful, 1 is returned, otherwise 0 is returned.

For verification of Chinese character input, we can use the following regular expression:

$pattern = '/^[u4e00-u9fa5]+$/u';

The meaning of this regular expression is to match strings that begin and end with Chinese characters. [u4e00-u9fa5] is the range of Chinese characters in Unicode encoding, and u means UTF-8 encoding is used.

Next, use the preg_match() function for verification:

if (preg_match($pattern, $input)) {
    echo "验证成功！";
} else {
    echo "验证失败！";
}

where $input is the string to be verified. If the verification is successful, output "Verification successful!"; otherwise, output "Verification failed!".

2. Handling special situations in Chinese character input

For some special situations, the above regular expression may need to be adjusted.

1. Full-width characters

In some cases, Chinese character input may use full-width characters instead of half-width characters. Therefore, the regular expression needs to be improved:

$pattern = '/^[x{3000}-x{303F}x{4e00}-x{9fa5}x{FF00}-x{FFEF}]+$/u';

Among them, x{3000}-x{303F} means matching full-width symbols, x{FF00}-x{FFEF } means matching full-width Chinese and English symbols.

2. Some Chinese Characters

In the input of some Chinese characters, some special symbols may appear, such as rare characters, Chinese radicals, etc. In order to be able to match these Chinese characters, the Unicode character set needs to be used.

$pattern = "/^[x{4e00}-x{9fa5}x{3400}-x{4DBF}x{20000}-x{2A6DF}x{2A700}-x{2B73F}x{2B740}-x{2B81F}x{2B820}-x{2CEAF}x{2CEB0}-x{2EBEF}x{2F800}-x{2FA1F}]+$/u";

Among them, x{3400}-x{4DBF} matches CJK extension A, x{20000}-x{2A6DF} matches CJK extension B, x{2A700}-x{2B73F} Matches CJK extension C, x{2B740}-x{2B81F} Matches CJK extension D, x{2B820}-x{2CEAF } Matches CJK extension E, x{2CEB0}-x{2EBEF} matches CJK extension F, x{2F800}-x{2FA1F} matches CJK compatible extension.

3. Spaces, newlines, tabs and other whitespace characters

In some cases, Chinese character input may contain spaces, newlines, tabs and other whitespace characters character. At this time, you need to add a statement that matches whitespace characters to the regular expression.

$pattern = '/^[\s\S]*|^[x{4e00}-x{9fa5}x{3400}-x{4DBF}x{20000}-x{2A6DF}x{2A700}-x{2B73F}x{2B740}-x{2B81F}x{2B820}-x{2CEAF}x{2CEB0}-x{2EBEF}x{2F800}-x{2FA1F}]+$/u';

Among them, [\s\S]* matches any blank character; | means or; the second half means matching Chinese characters.

By handling these special situations, Chinese character input can be verified more comprehensively.

3. Conclusion

Using PHP regular expressions to verify Chinese character input is a very practical skill. Through appropriate regular expressions, Chinese character input can be effectively verified. At the same time, appropriate adjustments to regular expressions based on actual conditions can better meet actual needs. Therefore, it is very necessary for developers to master the method of verifying Chinese character input with PHP regular expressions, and it is also part of programming skills.

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