How to use regularization to determine Chinese UTF-8 or GBK by PHP
This article mainly introduces PHP how to use regular judgment of Chinese UTF-8 or GBK, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand it.
UTF-8 matching: in javascript, it's easy to tell if a string is in Chinese. For example:
The code is as follows:
Var str = "php programming"
If (/ ^ [\ u4e00 -\ u9fa5] + $/ .test (str)) {
Alert ("the string is all in Chinese")
} else {
Alert ("the string is not all in Chinese")
}
In / / php, hexadecimal data is represented by\ x. So, transform it into the following code:
$str = "php programming"
If (preg_match ("/ ^ [\ x4e00 -\ x9fa5] + $/", $str)) {
Print ("the string is all in Chinese")
} else {
Print ("the string is not all in Chinese")
}
It seems that the report is not wrong, and the result of the judgment is also correct, but replacing the word $str with the word "programming" still shows that "the string is not all in Chinese". It seems that this judgment is not accurate enough. Important: I checked and found that for [\ x4e00 -\ x9fa5], I made an enhanced explanation of the rule of php. [\ x4e00 -\ x9fa5] is actually the concept of characters and character groups,\ x {hex}, expressing a hexadecimal number. It should be noted that hex can be 1-2 digits or 4 digits, but if it is 4 digits, curly braces must be added at the same time. If it is a hex greater than x {FF}, it must be used with the u modifier, otherwise an illegal error will occur.
Only regular characters that match full-width characters can be found on the Internet: ^ [\ x80 -\ xff] * ^ /. There can be no parentheses.
[\ u4e00 -\ u9fa5] can match Chinese, but PHP does not support it.
However, since\ x represents hexadecimal data, why is it different from the range\ x4e00 -\ x9fa5 provided in js? So I replaced it with the following code and found that it was really accurate:
The code is as follows:
$str = "php programming"
If (preg_match ("/ ^ [\ x {4e00} -\ x {9fa5}] + $/ u", $str)) {
Print ("the string is all in Chinese")
} else {
Print ("the string is not all in Chinese")
}
Know the final correct expression of matching Chinese characters with regular expressions under utf-8 coding in php-/ ^ [\ x {4e00} -\ x {9fa5}] + $/ u
Refer to the above article and write the following test code (copy the following code and save it as a .php file)
The code is as follows:
The code is as follows:
Enter characters (numbers, letters, Chinese characters, underscores):
GBK: preg_match ("/ ^ [" .chr (0xa1). "-" .chr (0xff). "A-Za-z0-9 _] + $/", $str); / / GB2312 Chinese character alphanumeric underscore regular expression.
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