C # Regular Expression

C # Regular Expression matching Basics

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 -./? % & =] *)? $ ".
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 ".

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 ,''))"

Extract the JavaScript code of the file name from the URL address using a regular expression.Program, The following result is page1

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)

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 * $)

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 ))

Symbol explanation:

Character	Description
\	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 (?).