C # Learning Log Day 6------Common Regular Expression examples

C # supports regular expression matching text, where the use of regular expressions is discussed, and examples of matching regular expressions are used.

1. Use regular expressions in VS

Using a regular expression in VS requires a using-System.Text.RegularExpressions namespace.

The namespace includes the following classes

Capture	Capturing results for a single expression
CaptureCollection	For a sequence of string captures
Group	Represents the result of a single capture
GroupCollection	Represents a rally for a capturing group
Match	Represents the result of matching a single regular expression
MatchCollection	Represents the application of a regular expression to a string in an iterative way
Regex	A regular expression that represents an immutable
RegexCompilationInfo	The compiled regular expression needs to provide information

which

Constructing regular expressions involves the Regex class, which includes: IsMatch (), replace (), split (), and other method methods in the Regex class, where the IsMatch (), replace (), split () methods are described

　　

(1) IsMatch () method;

The IsMatch () method is actually a return bool-worthy method, if the test character satisfies the regular expression return true otherwise returns false;

Example: Regex reg = new Regex ("022\\d{8}");//Constructs a phone number that starts with 022

String temp = "02222332332";

String temp1 = "02322332332";

Console.WriteLine (Reg. IsMatch (temp). ToString ());

Console.WriteLine (Reg. IsMatch (TEMP1). ToString ());

The result is True

False

(2) Replace () method;

The replace () method is actually a replacement method, replacing a matching regular expression matching pattern;

Example: replace @ In a mailbox and turn it into an at

Regex reg = new Regex ("\w{1,}@\w{1,}\."); /e-mail address

string email = "[email protected]";

Console.WriteLine (Reg. Replace (email, "@", "at");

Output is: whateveratqq.com

(3) Split () method;

The split () method is actually a split method, which is stored in a string array based on a matching regular expression;

Example: separating text with spaces and semicolons as separators

Regex reg = new Regex ("\s|;");

string mes = "Hello Nihao;zaijian";

String[] temp;

temp = Reg. Split (temp);

foreach (string str in temp) {

Console.WriteLine (str. ToString ());

}

Result: Hello

Nihao

Zaijian

2 The basic syntax for some C # regular rules is described below

Character matching syntax:

character Syntax	Grammatical explanations	Syntax Examples
\d	Matching numbers (0~9)	' \d ' matches 8, does not match 12;
\d	Match non-numeric	' \d ' matches C, does not match 3;
\w	Match any single character	' \w\w ' matches A3, does not match @3;
\w	Match Non-single character	' \w ' matches @, does not match C;
\s	Match white space characters	' \d\s\d ' matches 3 D, does not match ABC;
\s	Match non-null characters	' \s\s\s ' matches a#4, mismatch 3 D;
.	Match any character	' ... ' matches a$ 5, does not match line breaks;
[...]	Match any character in parentheses	[b-d] matches B, C, D, does not match E;
[^ ...]	Match non-bracket characters	[^b-z] matches a, does not match the character of B-z;

Repeating match syntax:

repeating Syntax	Grammatical explanations	Syntax Examples
N	Match N-Times characters	\d{3} matches \d\d\d, does not match \d\d or \d\d\d\d
{N,}	Matches n times and more than n times	\W{2} matches \w\w and \w\w\w above and does not match \w
{N,m}	Match n times on M times down	\s{1,3} matches \s,\s\s,\s\s\s, mismatch \s\s\s\s
?	Match 0 or 1 times	5. Match 5 or 0, mismatch not 5 and 0
+	Match one or more times	\s+ matches more than one \s, does not match more than one \s
*	Match more than 0 times	\w* matches more than 0 \w, does not match non-n*\w

Character positioning Syntax:

repeating Syntax	Grammatical explanations	Syntax Examples
^	Locate the back mode start position
$	The front pattern is at the end of the string
\a	Front mode start position
\z	Previous mode End position
\z	Previous mode end position (before line break)
\b	Match a word boundary
\b	Match a non-word boundary

Escape matching syntax:

Escape Syntax	characters involved (syntax explanation)	Syntax Examples
"\" + Actual character	\ . * + ? | ( ) { }^ $	For example: \ \ matches the character "\"
\ n	Match line break
\ r	Match carriage return
\ t	Match Horizontal Tabs
\v	Match vertical Tabs
\f	Match a page break
\nnn	Match a 8 binary ASCII
\xnn	Match a 16 binary ASCII
\unnnn	Match 4 x 16 binary Uniode
\c+ Capital Letters	Match Ctrl-Caps	Example: \cs-matching Ctrl+s

3, the following are some common regular matching statements:

1. Verify the user name and password: ("^[a-za-z]\w{5,15}$") the correct format: "[a-z][a-z]_[0-9]" composition, and the first word must be a letter 6~16 bit;

2. Verify the phone number: ("^ (\d{3.4}-) \d{7,8}$") correct format: xxx/xxxx-xxxxxxx/xxxxxxxx;

3. Verify the ID number (15-bit or 18-digit number): ("^\d{15}|\d{18}$");

4. Verify the email Address: ("^\w+ [-+.] \w+) *@\w+ ([-.] \w+) *\.\w+ ([-.] \w+) *$ ");

5. Only a string consisting of a number and 26 English letters can be entered: ("^[a-za-z0-9]+$");

6. Integer or decimal: ^[0-9]+\. {0,1} [0-9] {0,2}$

7. Enter only the number: "^[0-9]*$".

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

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

10. Enter only the digits of the m~n bit:. "^\d{m,n}$"

11. Enter only numbers that start with 0 and not 0: "^ (0|[ 1-9][0-9]*) $ ".

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

13. You can only enter positive real numbers with a decimal position: "^[0-9]+ (. [ 0-9]{1,3})? $ ".

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

15. You can only enter a non-zero negative integer: "^\-[1-9][]0-9" *$.

16. Only enter a character with a length of 3: "^. {3}$ ".

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

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

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

20. Verify that there are ^%& ',; =?$\ ' characters: ' [^%& ',; =?$\x22]+ '.

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

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

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

24. Verify one months of 31 days: "^ ((0?[ 1-9]) | ((1|2) [0-9]) |30|31) $ "correct format for;" 01 "~" 09 "and" 1 "~" 31 ".

C # Learning Log Day 6------Common Regular Expression examples