Summary of PHP regular expression matching Chinese problem analysis

Summary of PHP regular expression matching Chinese problem analysis_PHP tutorial

WBOY

Release： 2016-07-21 15:19:38

Original

778 people have browsed it

Copy code The code is as follows:

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

Run the above code and see what prompts there will be?

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
It turns out that 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{. ..}", 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.
So,
can be solved like this

Copy the code The code is as follows:

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

Match internal coded Chinese characters
Test according to the method he provided, the code is as follows:

Copy the code The code is as follows:

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

I found that this time I still misjudged whether it was Chinese or not. However, since the hexadecimal data represented by x, why is it different from the range x4e00-x9fa5 provided in js? So I changed to the following code:

Copy code The code is as follows:

 
$str = "php Programming"; 
if (preg_match("/^[x4e00-x9fa5]+$/u",$str)) { 
print("The string is all in Chinese"); 
} else { 
print("The string is not all in Chinese"); 
} 

What I thought was a sure success, unexpectedly, the warning occurred again:
Warning: preg_match() [function.preg-match]: Compilation failed: invalid UTF-8 string at offset 6 in test.php on line 3

It seems that there is another wrong expression, so I compared the expression in that article and wrapped "4e00" and "9fa5" with "{" and "}" respectively. I ran it again and found that it was really accurate:

Copy code The code is as follows:

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

I know the final correct expression for using regular expressions to match Chinese characters under UTF-8 encoding in PHP——/^[x{4e00}-x {9fa5}]+$/u,

Finally summarized

Copy the code The code is as follows:

 
//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”; 
} 

Double-byte character encoding range

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)