C # regular expression,

C # regular expression,

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Only numbers are allowed: "^ [0-9] * $ ".

Only n digits can be entered: "^ \ d {n} $ ".

You can only enter at least n digits: "^ \ d {n,} $ ".

Only m ~ can be input ~ N-digit: "^ \ d {m, n} $ ".

Only numbers starting with zero and non-zero can be entered: "^ (0 | [1-9] [0-9] *) $ ".

Only positive numbers with two decimal places can be entered: "^ [0-9] + (. [0-9] {2 })? $ ".

Only 1 ~ Positive number of three decimal places: "^ [0-9] + (. [0-9] {1, 3 })? $ ".

Only a non-zero positive integer can be entered: "^ \ +? [1-9] [0-9] * $ ".

Only a non-zero negative integer can be entered: "^ \-[1-9] [] 0-9" * $.

Only 3 characters can be entered: "^. {3} $ ".

You can only enter A string consisting of 26 English letters: "^ [A-Za-z] + $ ".

You can only enter a string consisting of 26 uppercase letters: "^ [A-Z] + $ ".

You can only enter a string consisting of 26 lower-case English letters: "^ [a-z] + $ ".

You can only enter a string consisting of a number and 26 English letters: "^ [A-Za-z0-9] + $ ".

You can only enter a string consisting of digits, 26 English letters, or underscores (_): "^ \ w + $ ".

Verify the User Password: "^ [a-zA-Z] \ w {5, 17} $". The correct format is: start with a letter, with a length of 6 ~ It can only contain characters, numbers, and underscores.

Check whether ^ % & ',; =? $ \ "And other characters:" [^ % & ',; =? $ \ X22] + ".

Only Chinese characters can be entered: "^ [\ u4e00-\ u9fa5] {0,} $"

Verify Email address: "^ \ w + ([-+.] \ w +) * @ \ w + ([-.] \ w + )*\. \ w + ([-.] \ w +) * $ ".

Verify InternetURL: "^ http: // ([\ w-] + \.) + [\ w-] + (/[\ w -./? % & =] *)? $ ".

Image extraction address:/(http (s )? \:\/\/)? (Www \.)? (\ W + \: \ d + )? (\/\ W +) + \. (png | gif | jpg | bmp | jpeg)/gi.

Verification phone number: "^ (\ d {3, 4}-) | \ d {3.4 }-)? \ D {7,8} $ "correct format:" XXX-XXXXXXX "," XXXX-XXXXXXXX "," XXX-XXXXXXX "," XXX-XXXXXXXX "," XXXXXXX "and" XXXXXXXX ".

Verify the ID card number (15 or 18 digits): "^ \ d {15} | \ d {18} $ ".

12 months of verification: "^ (0? [1-9] | 1 [0-2]) $ "the correct format is:" 01 "~ "09" and "1 "~ "12 ".

31 days of verification for a month: "^ (0? [1-9]) | (1 | 2) [0-9]) | 30 | 31) $ "the correct format is;" 01 "~ "09" and "1 "~ "31 ".

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

The following is a reference clip: S = "http://www.9499.net/page1.htm" S = s. replace (/(. * \/) {0,} ([^ \.] +). */ig, "$2 ") Alert (s)

 

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)

The following is a reference clip: 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 spaces at the beginning and end: (^ \ s *) | (\ s * $)

The following is a reference clip: 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:

The following is a reference clip:
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! ")
}
}

Symbol explanation:
\
Mark the next character as a special character, a literal character, or a backward reference, or an octal escape character. For example, 'n' matches the character "n ". '\ N' matches a line break. The sequence '\' matches "\" and "\ (" matches "(".
^
Matches the start position of the input string. If the Multiline attribute of the RegExp object is set, ^ matches the position after '\ n' or' \ R.
$
Matches the end position of the input string. If the Multiline attribute of the RegExp object is set, $ also matches the position before '\ n' or' \ R.
*
Matches the previous subexpression zero or multiple times. For example, zo * can match "z" and "zoo ". * Is equivalent to {0 ,}.
+
Match the previous subexpression once or multiple times. For example, 'Zo + 'can match "zo" and "zoo", but cannot match "z ". + Is equivalent to {1 ,}.
?
Match the previous subexpression zero or once. For example, "do (es )? "Can match" do "in" do "or" does ".? It is equivalent to {0, 1 }.
{N}
N is a non-negative integer. Match n times. For example, 'O {2} 'cannot match 'O' in "Bob", but can match two o in "food.
{N ,}
N is a non-negative integer. Match at least n times. For example, 'O {2,} 'cannot match 'O' in "Bob", but can match all o in "foooood. 'O {1,} 'is equivalent to 'o + '. 'O {0,} 'is equivalent to 'o *'.
{N, m}
Both m and n are non-negative integers, where n <= m. Match at least n times and at most m times. For example, "o {1, 3}" matches the first three o in "fooooood. 'O {0, 1} 'is equivalent to 'o? '. Note that there must be no space between a comma and two numbers.
?
When this character is followed by any other delimiter (*, + ,?, The matching mode after {n}, {n ,}, {n, m}) is not greedy. The non-Greedy mode matches as few searched strings as possible, while the default greedy mode matches as many searched strings as possible. For example, for strings "oooo", 'O ++? 'Will match a single "o", and 'O +' will match all 'O '.
.
Matches any single character except "\ n. To match any character including '\ n', use a pattern like' [. \ n.
(Pattern)
Match pattern and obtain this match. The obtained match can be obtained from the generated Matches set. The SubMatches set is used in VBScript, and $0… is used in JScript... $9 attribute. To match the parentheses, use ''or ′'.
(? : Pattern)
Matches pattern but does not get the matching result. That is to say, this is a non-get match and is not stored for future use. This is useful when you use the "or" character (|) to combine each part of a pattern. For example, 'industr (? : Y | ies) is a simpler expression than 'industry | industries.
(? = Pattern)
Forward pre-query: matches the search string at the beginning of any string that matches the pattern. This is a non-get match, that is, the match does not need to be obtained for future use. For example, 'windows (? = 95 | 98 | NT | 2000) 'can match "Windows" in "Windows 2000", but cannot match "Windows" in "Windows 3.1 ". Pre-query does not consume characters, that is, after a match occurs, the next matching search starts immediately after the last match, instead of starting after the pre-query characters.
(?! Pattern)
Negative pre-query: matches the search string at the beginning of any string that does not match pattern. This is a non-get match, that is, the match does not need to be obtained for future use. For example, 'windows (?! 95 | 98 | NT | 2000) 'can match "Windows" in "Windows 3.1", but cannot match "Windows" in "Windows 2000 ". Pre-query does not consume characters. That is to say, after a match occurs, the next matching search starts immediately after the last match, instead of starting after the pre-query characters.
X | y
Match x or y. For example, 'z | food' can match "z" or "food ". '(Z | f) ood' matches "zood" or "food ".
[Xyz]
Character Set combination. Match any character in it. For example, '[abc]' can match 'A' in "plain '.
[^ Xyz]
Negative value character set combination. Match any character not included. For example, '[^ abc]' can match 'p' in "plain '.
[A-z]
Character range. Matches any character in the specified range. For example, '[a-z]' can match any lowercase letter in the range of 'A' to 'Z.
[^ A-z]
Negative character range. Matches any character that is not within the specified range. For example, '[^ a-z]' can match any character that is not in the range of 'A' to 'Z.
\ B
Match A Word boundary, that is, the position between a word and a space. For example, 'er \ B 'can match 'er' in "never", but cannot match 'er 'in "verb '.
\ B
Match non-word boundary. 'Er \ B 'can match 'er' in "verb", but cannot match 'er 'in "never '.
\ Cx
Match the control characters specified by x. For example, \ cM matches a Control-M or carriage return character. The value of x must be either a A-Z or a-z. Otherwise, c is treated as an original 'C' character.
\ D
Match a numeric character. It is equivalent to [0-9].
\ D
Match a non-numeric character. It is equivalent to [^ 0-9].
\ F
Match a form feed. It is equivalent to \ x0c and \ cL.
\ N
Match A linefeed. It is equivalent to \ x0a and \ cJ.
\ R
Match a carriage return. It is equivalent to \ x0d and \ cM.
\ S
Matches any blank characters, including spaces, tabs, and page breaks. It is equivalent to [\ f \ n \ r \ t \ v].
\ S
Match any non-blank characters. It is equivalent to [^ \ f \ n \ r \ t \ v].
\ T
Match a tab. It is equivalent to \ x09 and \ cI.
\ V
Match a vertical tab. It is equivalent to \ x0b and \ cK.
\ W
Match any word characters that contain underscores. It is equivalent to '[A-Za-z0-9 _]'.
\ W
Match any non-word characters. It is equivalent to '[^ A-Za-z0-9 _]'.
\ Xn
Match n, where n is the hexadecimal escape value. The hexadecimal escape value must be determined by the length of two numbers. For example, '\ x41' matches "". '\ X041' is equivalent to '\ x04' & "1 ". The regular expression can use ASCII encoding ..
\ Num
Matches num, where num is a positive integer. References to the obtained matching. For example, '(.) \ 1' matches two consecutive identical characters.
\ N
Identifies an octal escape value or a backward reference. If at least n subexpressions are obtained before \ n, n is backward referenced. Otherwise, if n is an octal digit (0-7), n is an octal escape value.
\ Nm
Identifies an octal escape value or a backward reference. If at least one child expression is obtained before \ nm, the nm is backward referenced. If at least n records are obtained before \ nm, n is a backward reference followed by text m. If none of the preceding conditions are met, if n and m are Octal numbers (0-7), \ nm matches the octal escape value nm.
\ Nml
If n is an octal number (0-3) and m and l are Octal numbers (0-7), the octal escape value nml is matched.
\ Un
Match n, where n is a Unicode character represented by four hexadecimal numbers. For example, \ u00A9 matches the copyright symbol (?).

Application:

C # Regular Expression # region Regular Expression string // <summary> // Regular Expression string // </summary> public class StrRegex {# region Regular Expression replacement string/ // <summary> /// Replace the string with a regular expression /// </summary> /// <param name = "inputString"> string content </param> /// <param name = "pattern"> replacement character </param> /// <param name = "replaceStr"> replacement value </param> /// <returns> </returns> public static string RegexReplace (string inputString, string pattern, string replaceStr) {try {Return Regex. replace (inputString, pattern, replaceStr);} catch (Exception e) {return e. message ;}} # endregion # region determine whether the string is a positive integer // <summary> // determine whether the string is a positive integer /// </summary> /// <param name = "objString"> The string to be matched </param> // <returns> returns the true value, true: match; false: Mismatch </returns> public static bool IsInt (String objString) {Regex myReg = new Regex (@ "^ \ d + $"); return myReg. isMatch (objString) ;}# endregion # regi On determines whether all input strings are English (Case Insensitive) /// <summary> // determines whether all input strings are English (Case Insensitive) /// </summary> /// <param name = "objString"> the string to be matched </param> /// <returns> returns the true value, true: match; false: Mismatch </returns> public static bool isEnglishString (String objString) {Regex myReg = new Regex (@ "^ [a-zA-Z] + $ "); return myReg. isMatch (objString );} # endregion // <summary> // return the number in the string /// </summary> /// <param name = "objString"> </param> /// <Returns> </returns> public static string RunNumber (string objString) {return Regex. match (objString, "[0-9] + "). value. toString ();} /// <summary> /// returns the character on the left of the string /// </summary> /// <param name = "objString"> </param> /// <returns> </returns> public static string RunLeftString (string objString) {return Regex. match (objString, "[% */+ -. a-Za-z] + "). value. toString () ;}//< summary> /// return the character on the right of the string /// </su Mmary> /// <param name = "objString"> </param> /// <returns> </returns> public static string RunRightString (string objString) {return Regex. match (objString, "[% */+ -. a-Za-z] + $ "). value. toString ();} /// <summary> /// return the characters in the string /// </summary> /// <param name = "objString"> </param> // <returns> </returns> public static string RunString (string objString) {return Regex. match (objString, "[A-Za-z] + "). value. T OString ();} # region judge whether the input string is Chinese // <summary> /// determine whether the input string is Chinese // </summary> /// <param name = "objString"> the string to be matched </param> // <returns> returns the true value, true: match; false: Mismatch </returns> public static bool isChinese (String objString) {Regex myReg = new Regex (@ "^ [\ u4e00-\ u9fa5] + $"); return myReg. isMatch (objString) ;}# endregion # region determines whether the input string is an English or a number (English is case insensitive) /// <summary> /// determines whether the input string is an English or a number (English is case insensitive )/// </Summary> /// <param name = "objString"> the string to be matched </param> /// <returns> returns the true value. true: match; false: mismatch </returns> public static bool isEngNum (String objString) {Regex myReg = new Regex (@ "^ [*/+-a-zA-Z0-9] + $"); return myReg. isMatch (objString) ;}# endregion # region determines whether the input string is an English A-D and number (English restrictions are case-insensitive between A-D) /// <summary> /// determines whether the input string is an English A-D and number (English only between A-D) /// </summary> /// <param name = "objString"> the character to be matched String </param> // <returns> returns the true value, true: matching; false: not matching </returns> public static bool isEngNumMax (String objString) {Regex myReg = new Regex (@ "^ [a-dA-D0-9] + $"); return myReg. isMatch (objString );} # endregion # Check whether region is a combination of English letters and numbers /// <summary> /// check whether it is a combination of English letters and numbers /// </summary> /// <param name = "objString"> </param> // <returns> </returns> public static bool InEngNum (string objString) {// Regex myReg = new Regex (@ "^ (?! [0-9] + $) [a-zA-Z0-9] {25} $ "); // return myReg. isMatch (objString); "^ [a-zA-Z] \ w {5, 17} $" return Regex. isMatch (objString, @ "^ [*/+-a-zA-Z0-9] {} $");} # endregion # region judge whether the input string is English, number, chinese (English is case insensitive) /// <summary> /// determines whether the input string is English, numbers, and Chinese (English is case insensitive) /// </summary> /// <param name = "objString"> the string to be matched </param> /// <returns> returns the true value, true: match; false: Mismatch </returns> public static bool isChineseEngNum (String objString) {Regex myReg = new Regex (@ "^ [\ u4e00-\ u9fa5a-zA-Z0-9] + $"); return myReg. isMatch (objString );} # endregion # region determines whether the input string is a decimal number. /// <summary> /// determines whether the input string is a decimal number. /// </summary> /// <param name =" objString "> the string to be matched </param> // <returns> returns the true value, true: match; false: Mismatch </returns> public static bool isFloat (String objString) {Regex myReg = new Regex (@ "^ [0-9] + [.] [0-9] + | [0-9] + $ "); return myReg. isMatch (objString );} # Endregion # region determine whether the date format is valid // <summary> // determine whether the date format is valid // </summary> /// <param name = "objString "> </param> /// <returns> </returns> public static bool IsDate (String objString) {Regex myReg = new Regex (@ "\ B (? <Year> \ d {2, 4 })-(? <Month> \ d {1, 2 })-(? <Day> \ d {1, 2}) \ B "); return myReg. isMatch (objString );} # endregion # region test whether the string matches the regular expression // <summary> // test whether the string matches the regular expression // </summary> // <param name = "str"> string to be matched </param> // <param name = "regString"> regular string (for example: ^ [1-9] {1 }$) </param> // <returns> returns the true value. true: match; false: mismatch </returns> public static bool IsFitStrings (String str, String regString) {Regex objPattern = new Regex (regString); bool returnValue = ObjPattern. isMatch (str); return returnValue ;} # endregion # region determine whether the string is a mobile phone number or PHS number // <summary> // determine whether the string is a mobile phone number or PHS number /// </summary> /// <param name = "telNumber"> the string to be matched </param> // <returns> returns the true value, true: match; false: Mismatch </returns> public static bool IsMobile (string telNumber) {if (telNumber = "") return false; regex myReg = new Regex (@ "^ (\ d {11,12}) | (\ d {7}) $"); return myReg. isMatch (telNumber );}# Endregion # region determine whether the string is an Email address // <summary> /// determine whether the string is an Email address /// </summary> /// <param name = "email "> the string to be matched </param> // <returns> returns the true value, true: match; false: Mismatch </returns> public static bool IsEmail (string email) {if (email = "") {return false ;} regex myReg = new Regex (@ "^ \ w + ([-+.] \ w +) * @ \ w + ([-.] \ w + )*\. \ w + ([-.] \ w +) * $ "); return myReg. isMatch (email) ;}# endregion # region determines whether the string is a landline (for example, xxx-xxxxxxx-xx) X) /// <summary> /// determines whether the string is a landline (for example, xxx-xxxxxxx-xxx) /// </summary> /// <param name = "tel"> string to be matched </param> /// <returns> returns the true value, true: match; false: Mismatch </returns> public static bool IsTel (string tel) {if (tel = "") return false; regex myReg = new Regex (@ "^ (\ d {3, 4} \) | \ d {3, 4 }-)? \ D {7, 8} (-\ d {1, 5 })? $ "); Return myReg. isMatch (tel );} # endregion # region determine whether it is a Zip code // <summary> /// determine whether it is a Zip code /// </summary> /// <param name = "Zip"> </param> // <returns> </returns> public static bool IsValidZip (string Zip) {return Regex. isMatch (Zip, @ "^ [a-z0-9] {} $ ");} # endregion # Check whether region is a valid ID card number /// <summary> /// check whether it is a valid ID card number /// </summary> /// <param name = "IdCard"> </param> /// <returns> </returns> public static bool IsIdCard (string IdCard) {return Regex. isMatch (IdCard, @ "^ \ d {15} | \ d {18} $ ");} # endregion # region returns the split string /// <summary> /// returns the split string /// </summary> /// <param name = "Str"> string set </param> /// <param name = "spliststr"> specify delimiter </param> /// <returns> </returns> public static string FindStr (string str, string spliststr) {string [] str2 = System. text. regularExpressions. regex. split (Str, @ "[" + spliststr + "] +"); foreach (string I in str2) {return I. toString () ;}return "" ;}# endregion }# endregion