Some commonly used regular expressions in PHP_PHP tutorial

Regular expression to match Chinese characters: [u4e00-u9fa5]
Match double-byte characters (including Chinese characters): [^x00-xff]
Application: Calculate the length of a string (a double-byte character The length is counted as 2, and the ASCII character is counted as 1)

String.prototype.len=function(){return this.replace([^x00-xff]/g,"aa").length;}
Regular expression to match empty lines: [s| ]*
Regular expression to match HTML tags: /<(.*)>.*|<(.*) /> /
Regular expression to match leading and trailing spaces: (^s*)|(s*$)
Application: There is no trim function like vbscript in JavaScript, so we can use this expression to achieve it, as follows:

String.prototype.trim = function() {
return this.replace(/(^s*)|(s*$)/g, "");
}
Use regular expressions to decompose and convert IP addresses:
The following is a javascript program that uses regular expressions to match IP addresses and convert IP addresses into corresponding values:

function IP2V(ip) {
re=/(d ).(d ).(d ).(d )/g //Regular expression matching IP address
if(re.test(ip)) {
return RegExp.*Math .pow(255,3)) RegExp.*Math.pow(255,2)) RegExp.*255 RegExp.*1
}
else {
throw new Error("Not a valid IP address !")
}
}
However, if the above program does not use regular expressions, it may be simpler to use the split function to decompose it directly. The program is as follows:

var ip="10.100. 20.168"
ip=ip.split(".")
alert("The IP value is: " (ip[0]*255*255*255 ip[1]*255*255 ip[2]* 255 ip[3]*1))
Regular expression matching email addresses: w ([- .]w )*@w ([-.]w )*.w ([-.]w )*
Regular expression to match URL: http://([w-] .) [w-] (/[w- ./?%&=]*)?
Use regular expression to remove strings Algorithm program for repeated characters in:

var s="abacabefgeeii"
var s1=s.replace(/(.).*/g,"")
var re=new RegExp ("[" s1 "]","g")
var s2=s.replace(re,"")
alert(s1 s2) //The result is: abcefgi
Use regular expressions from A javascript program that extracts file names from URL addresses. The following result is page1

s="http://www.9499.net/page1.htm"
s=s.replace(/(.* /)([^.] ).*/ig,"")
alert(s)
Use regular expressions to limit the input content of the text box in the web form:

http://www.bkjia.com/PHPjc/445169.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/445169.htmlTechArticleRegular expression matching Chinese characters: [u4e00-u9fa5] Matches double-byte characters (including Chinese characters) : [^x00-xff] Application: Calculate the length of a string (the length of a double-byte character is counted as 2, A...