Solutions to several problems with PHP regular expression matching Chinese

$str = 'People's Republic of China 123456789abcdefg';
echo preg_match("/^[u4e00-u9fa5_a-zA-Z0-9]{3,15}$",$strName);
?>

Run the above code, you will be prompted: Warning: preg_match(): Compilation failed: PCRE does not support L, l, N, P, p, U, u, or X at offset 3 in F:wwwrootphptest.php on line 2

The reason is: the following Perl escape sequences are not supported in PHP regular expressions: L, l, N, P, p, U, u, or X

In UTF-8 mode, "x{...}" is allowed, and the content in the curly brackets is a string representing a hexadecimal number.

The original hexadecimal escape sequence xhh matches a double-byte UTF-8 character if its value is greater than 127. Solution:

preg_match("/^[x80-xff_a-zA-Z0-9]{3,15}$",$strName);
preg_match('/[x{2460}-x{2468}] /u', $str);

match internal code Chinese characters Test it as he provided:

$str = "php programming";
if (preg_match("/^[x{2460}-x{2468}]+$/u",$str)) {
 print("The string is all Chinese");
} else {
print("The string is not all Chinese");
}
?>

This operation is still correct Determining whether it is Chinese is abnormal. However, since the hexadecimal data represented by x, why is it different from the range x4e00-x9fa5 provided in js? So the code was modified as follows:

$str = "php programming";
if (preg_match("/^[x4e00-x9fa5]+$/u",$str)) {
print("this string All are Chinese");
} else {
print("This string is not all Chinese");
}
?>

warning is generated again: Warning: preg_match() [function.preg-match]: Compilation failed: invalid UTF-8 string at offset 6 in test.php on line 3 Then I modified it and wrapped "4e00" and "9fa5" with "{" and "}" respectively. I ran it again and found that it was accurate this time:

$str = "php programming";
if (preg_match("/^[x{4e00}-x{9fa5}]+$/u",$str)) {
 print("This string is all Chinese");
} else {
print("This string is not all Chinese");
}
?>

I know utf in php The final correct expression for matching Chinese characters using regular expressions under -8 encoding: /^[x{4e00}-x{9fa5}]+$/u，

The final version of the implementation code:

//if (preg_match("/^[".chr(0xa1)."-".chr(0xff)."]+$/", $str)) { / /Can only be used in the case of GB2312
if (preg_match("/^[x7f-xff]+$/", $str)) { //Compatible with gb2312, utf-8
echo "Correct input";
} else {
echo "Wrong input";
}
?>

Example 2,

$action = trim($_GET['action']);
if($action == "sub")
{
$str = $_POST['dir'];
//if(!preg_match("/^[".chr(0xa1)."-".chr(0xff)."A-Za-z0-9_]+$/",$str)) //GB2312 Chinese characters Alphanumeric underline regular expression
if(!preg_match("/^[x{4e00}-x{9fa5}A-Za-z0-9_]+$/u",$str)) //UTF-8 Chinese characters Number underline regular expression
{
 echo "The [".$str."] you entered contains illegal characters";
}
else
{
 echo "The [".$str."] you entered is completely legal and passed!";
}
}
?>

Input characters (numbers, letters, Chinese characters, underscores):

Attached, the double-byte character encoding range in PHP

1. GBK (GB2312/GB18030)

x00-xff GBK double-byte encoding range x20-x7f ASCII xa1-xff Chinese gb2312 x80-xff Chinese gbk

2. UTF-8 (Unicode)

u4e00-u9fa5 (Chinese) x3130-x318F (Korean xAC00-xD7A3 (Korean) u0800-u4e00 (Japanese)

Let’s introduce these, I hope it will help everyone understand the method of regular matching Chinese in PHP. Programmer's Home, I wish you all the best in your studies and progress.