Some common regular expressions in PHP

Some common regular expressions in PHP. read some common regular expressions in PHP and match the regular expressions of Chinese characters: [\ u4e00-\ u9fa5] to match double-byte characters (including Chinese characters ): [^ \ x00-\ xff] application: calculates the length of a String (two-byte length: 2, ASCII character: 1) String. prototype. len = function () {ret

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:/<(. *)>. * <\/> | <(. *) \/>/

Regular expression that matches spaces at the beginning and end: (^ \ 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. * 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 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 ))

The 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 (/(.). */g ,"")
Var re = new RegExp ("[" + s1 + "]", "g ")
Var s2 = s. replace (re ,"")
Alert (s1 + s2) // The result is: abcefgi

Use a regular expression to extract a javascript program with a file name from a URL. the following result is page1.

S = "http://www.9499.net/page1.htm"
S = s. replace (/(. * \/) ([^ \.] +). */ig ,"")
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 full-width characters using regular expressions:

Onkeyup = "value = value. replace (/[^ \ uFF00-\ uFFFF]/g, '')" onbeforepaste = "clipboardData. setData ('text', clipboardData. getData ('text '). replace (/[^ \ uFF00-\ uFFFF]/g ,''))"

You can only enter numbers using regular expressions:

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 ,''))"