PHP regular expression matching Chinese problem analysis, _PHP tutorial

PHP regular expression matching Chinese problem analysis,

$str = '中华人民共和国123456789abcdefg';<br />echo preg_match("/^[u4e00-u9fa5_a-zA-Z0-9]{3,15}$",$strName);

Run the above code and see what prompts will appear?

Warning: preg_match(): Compilation failed: PCRE does not support L, l, N, P, p, U, u, or X at offset 3 in F:http://www.hzhuti.com /nokia/5800/ 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{...}" 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.
So,
it can be solved like this

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

Matches the internal coded Chinese characters
and tests it according to the method he provided. The code is as follows:

The code is as follows Copy the code

$str = "php编程";<br />if (preg_match("/^[x{2460}-x{2468}]+$/u",$str)) {<br />print("该字符串全部是中文");<br />} else {<br />print("该字符串不全部是中文");<br />}

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 it to the following code:

$str = "php编程";<br />if (preg_match("/^[x4e00-x9fa5]+$/u",$str)) {<br />print("该字符串全部是中文");<br />} else {<br />print("该字符串不全部是中文");<br />}

What I thought was a sure success, unexpectedly, a 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 a wrong expression again, so I compared the expression in that article and wrapped "4e00" and "9fa5" with "{" and "}" respectively. I ran it again and found that It’s really accurate:

$str = "php编程";<br />if (preg_match("/^[x{4e00}-x{9fa5}]+$/u",$str)) {<br />print("该字符串全部是中文");<br />} else {<br />print("该字符串不全部是中文");<br />}<br /> 

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

Finally concluded

//if (preg_match(&ldquo;/^[".chr(0xa1)."-".chr(0xff)."]+$/&rdquo;, $str)) { //只能在GB2312情况下使用<br />if (preg_match(&ldquo;/^[x7f-xff]+$/&rdquo;, $str)) { //兼容gb2312,utf-8<br />echo &ldquo;正确输入&rdquo;;<br />} else {<br />echo &ldquo;错误输入&rdquo;;<br />}

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)