Some common regular expressions in PHP

Regular expressions that match Chinese characters: [\U4E00-\U9FA5]

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

Application: Computes the length of the string (a double-byte character length meter 2,ascii character 1)

String.prototype.len=function () {return This.replace ([^\x00-\xff]/g, "AA"). Length;}
A regular expression that matches a blank row: \n[\s|] *\r

Regular expression matching HTML tags:/< (. *) >.*<\/>|< (. *) \/>/

Matching a regular expression with a trailing space: (^\s*) | (\s*$)

Application: JavaScript does not have a trim function like VBScript, we can use this expression to implement, as follows:

String.prototype.trim = function () {
Return This.replace (/(^\s*) | ( \s*$)/g, "");
}
To decompose and transform an IP address using a regular expression:

The following is a JavaScript program that uses a regular expression to match an IP address and converts an IP address to a corresponding numeric value:

function IP2V (IP) {
re=/(\d+) \. (\d+) \. (\d+) \. (\d+)/g//matching the regular expression of the 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 a regular expression, and the split function directly to decompose may be simpler, the program is as follows:

var ip= "10.100.20.168"
Ip=ip.split (".")
Alert ("IP value is:" + (IP[0]*255*255*255+IP[1]*255*255+IP[2]*255+IP[3]*1))
Regular expression matching an email address: \w+ ([-+.] \w+) *@\w+ ([-.] \w+) *\.\w+ ([-.] \w+) *

A regular expression that matches URL URLs: http://([\w-]+\.) +[\w-]+ (/[\w-/?%&=]*)?

An algorithmic program that uses regular expressions to remove repetitive characters from a string:

var s= "Abacabefgeeii"
var s1=s.replace (/(.). */g, "")
var re=new RegExp ("[" +s1+ "]", "G")
var s2=s.replace (Re, "")
Alert (S1+S2)//Result: ABCEFGI
JavaScript program that extracts the filename from the URL address using a regular expression, the following result is Page1

S= "Http://www.9499.net/page1.htm"
S=s.replace (/(. *\/) ([^\.] +). */ig, "")
Alert (s)
Use regular expressions to restrict the entry of text boxes in a Web page's form:

Only Chinese can be entered with regular expression restrictions:

Onkeyup= "Value=value.replace (/[^\u4e00-\u9fa5]/g,") "Onbeforepaste=" Clipboarddata.setdata (' text ', Clipboarddata.getdata (' text '). Replace (/[^\u4e00-\u9fa5]/g, ') "
Only full-width characters can be entered with regular expression restrictions:

Onkeyup= "Value=value.replace (/[^\uff00-\uffff]/g,") "Onbeforepaste=" Clipboarddata.setdata (' text ', Clipboarddata.getdata (' text '). Replace (/[^\uff00-\uffff]/g, ') "
Only numbers can be entered with regular expression restrictions:

Onkeyup= "Value=value.replace (/[^\d]/g,") "Onbeforepaste=" Clipboarddata.setdata (' text ', Clipboarddata.getdata (' Text '). Replace (/[^\d]/g, ') "
You can only enter numbers and English with regular expression restrictions:

Onkeyup= "Value=value.replace (/[\w]/g,") "Onbeforepaste=" Clipboarddata.setdata (' text ', Clipboarddata.getdata (' Text '). Replace (/[^\d]/g, ') "