A hodgedge of Regular Expressions

Collect common regular expressions.

Regular expressions are used for string processing, form verification, and other occasions. They are practical and efficient, but they are always not sure when used, so they often need to be checked online. I will add some frequently-used expressions to my favorites for memo. This post is updated at any time.

Regular Expressions matching common user names:

Private bool isvalidusername (string strusername)
{
Return (RegEx. ismatch (strusername, @ "^ (\ W {3, 15}) $"); // The length of the user name must be between 3 and 15 and can only be letters, numbers, or underscores!
}

Regular Expression matching Chinese characters: [u4e00-u9fa5]

Match double byte characters (including Chinese characters): [^ x00-xff]

Application: Calculate the length of a string (two-byte length Meter 2, ASCII character meter 1)

String. Prototype. Len = function () {return this. Replace ([^ x00-xff]/g, "AA"). length ;}

Regular Expression for matching empty rows: N [S |] * R

Regular Expressions matching HTML tags:/<(. *)>. * </1> | <(. *)/>/

Regular Expression matching the first and last spaces: (^ s *) | (S * $)

Application: JavaScript does not have trim functions like VBScript. We can use this expression to implement it, as shown below:

String. Prototype. Trim = function ()
{
Return this. Replace (/(^ s *) | (S * $)/g ,"");
}

Use regular expressions to break down and convert IP addresses:

The following is a javascript program that uses regular expressions to match IP addresses and convert IP addresses to corresponding values:

Function ip2v (IP)
{
Re =/(D +). (D +)/g // Regular Expression matching IP addresses
If (Re. Test (IP ))
{
Return Regexp. $1 * Math. Pow (255) + Regexp. $2 * Math. Pow () + Regexp. $3 * + Regexp. $4*1
}
Else
{
Throw new error ("not a valid IP address! ")
}
}

However, if the above program does not use regular expressions, it may be easier to directly use the split function to separate them. The program is as follows:

VaR IP = "10.100.0000168"
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 the email address: W + ([-+.] W +) * @ w + ([-.] W + )*. W + ([-.] W + )*

The regular expression matching the URL: http: // ([w-] +.) + [w-] + (/[w -./? % & =] *)?

Algorithm program that uses regular expressions to remove repeated characters in a string:

VaR S = "abacabefgeeii"
VaR S1 = S. Replace (/(.). * 1/g, "$1 ")
VaR Re = new Regexp ("[" + S1 + "]", "G ")
VaR S2 = S. Replace (Re ,"")
Alert (S1 + S2) // The result is: abcefgi

I used to post on csdn to seek an expression to remove repeated characters, but I couldn't find it. This is the simplest implementation method I can think. The idea is to use the back-to-back reference to retrieve repeated characters, then create a second expression with repeated characters, get non-repeated characters, and connect the two. This method may not apply to strings with character order requirements.

Javascript programs that extract file names from URLs using regular expressions. the following result is page1.

S = "http://www.9499.net/page1.htm"
S = S. Replace (/(. */) {0,} ([^.] +). */ig, "$2 ")
Alert (s)

Use regular expressions to restrict text box input in a webpage form:

You can only enter Chinese characters using regular expressions: onkeyup = "value = value. replace (/[^ u4E00-u9FA5]/g, ''') "onbeforepaste =" clipboardData. setdata (''text'', clipboardData. getdata (''text ''). replace (/[^ u4E00-u9FA5]/g ,''''))"

You can only enter the full-width characters: onkeyup = "value = value. replace (/[^ uFF00-uFFFF]/g, ''') "onbeforepaste =" clipboardData. setdata (''text'', clipboardData. getdata (''text ''). replace (/[^ uFF00-uFFFF]/g ,''''))"

Use a regular expression to limit that only numbers can be entered: onkeyup = "value = value. replace (/[^ d]/g, ''') "onbeforepaste =" clipboardData. setdata (''text'', clipboardData. getdata (''text ''). replace (/[^ d]/g ,''''))"

You can only enter numbers and English letters using regular expressions: onkeyup = "value = value. replace (/[w]/g, ''') "onbeforepaste =" clipboardData. setdata (''text'', clipboardData. getdata (''text ''). replace (/[^ d]/g ,''''))"

Msdn help
Http://www.microsoft.com/china/msdn/library/webservices/asp.net/regexnet.mspx? MFR = true

Regular Expression Library http://www.regexlib.com/

Regular Expressions discuss list http://aspadvice.com/login.aspx? Returnurl = % 2 fsignup % 2flist. aspx % 3fl % 3d68% 26C % 3d16 & l = 68 & C = 16

Regular Expression Forum http://forums.regexadvice.com/

Regular Expressions web log http://blogs.regexadvice.com/

Mastering Regular Expressions (O 'Reilly) by Jeffrey Friedl http://www.regex.info/

. Net regular expression reference http://msdn.microsoft.com/library/en-us/cpref/html/frlrfSystemTextRegularExpressions.asp

JScript, regular expression, syntax, http://www.msdn.microsoft.com/library/en-us/script56/html/js56jsgrpRegExpSyntax.asp

Regular Expression Information http://www.regular-expressions.info/

Other references:
Topic: JS Regular Expression detailed explanation [favorites] http://www.javaeye.com/topic/30728
Use regular expressions to thoroughly remove HTML \ CSS \ script code http://www.cnblogs.com/xucanzhao/archive/2006/09/18/507108.aspx