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This article mainly explains "what is a golang regular expression". The content of the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what is a golang regular expression".

Go (also known as Golang) is a static strongly typed and compiled language developed by Robert Griesemer,Rob Pike and Ken Thompson of Google. The syntax of Go is similar to that of C, but its functions are: memory security, GC (garbage collection), structure and CSP-style concurrent computing.

Robert Grismo (Robert Griesemer), Rob Parker (Rob Pike) and Ken Thompson (Ken Thompson) began designing Go in September 2007, and later Ian Lance Taylor and Russ Cox joined the project. Go is developed based on the Inferno operating system. Go officially announced its launch in November 2009 as an open source project, and implemented on Linux and Mac OS X platforms, and later added the implementation under the Windows system. In 2016, Go was selected as the "best language of TIOBE 2016" by software evaluation company TIOBE. Currently, Go releases a second-tier version every six months (that is, upgrading from A.X to A.Y).

Let's take a look at golang regular expressions.

1 number: ^ [0-9] * $

2 n-digit number: ^\ d {n} $

3 at least n digits: ^\ d {n,} $

The number of 4 mmurn digits: ^\ d {mcentine n} $

5 numbers starting with zero and non-zero: ^ (0 | [1-9] [0-9] *) $

6 A number with up to two decimal places beginning with a non-zero: ^ ([1-9] [0-9] *) + (. [0-9] {1J 2})? $

7 positive or negative numbers with 1-2 decimal places: ^ (\ -)?\ d + (\.\ d {1Magne2})? $

8 positive, negative, and decimal: ^ (\-|\ +)?\ d + (\.\ d +)? $

9 A positive real number with two decimal places: ^ [0-9] + (. [0-9] {2})? $

10 A positive real number with 1 to 3 decimal places: ^ [0-9] + (. [0-9] {1Jue 3})? $

11 non-zero positive integers: ^ [1-9]\ During $or ^ ([1-9] [0-9] *) {1 ~ (3)} $or ^\ +? [1-9] [0-9] * $

12 non-zero negative integers: ^\-[1-9] [] 0-9 "* $or ^-[1-9]\ $

13 non-negative integers: ^\ DX $or ^ [1-9]\ d* | 0 $

14 non-positive integer: ^-[1-9]\ d* | 0$ or ^ ((-\ d+) | (0 +)) $

15 non-negative floating point numbers: ^\ d + (\.\ d +)? $or ^ [1-9]\ d *.\ d * | 0.\ d * [1-9]\ d * | 0?\ .0 + | 0 $

16 non-positive floating point number: ^ ((-\ d + (\.\ d +)?) | (0 + (\ .0 +)?)) $or ^ (- ([1-9]\ d *\.\ d * | 0.\ d * [1-9]\ d *)) | 0?\ .0 + | 0 $

17 positive floating point number: ^ [1-9]\ d *\.\ d * | 0\.\ d * [1-9]\ d * or ^ (([0-9] +. [0-9] * [1-9] [0-9] *) | ([0-9] * [1-9] [0-9] *. [0-9] +) | ([0-9] * [1-9] [0-9] *) $

18 negative floating point numbers: ^-([1-9]\ d *\.\ d * | 0\.\ d * [1-9]\ d *) $or ^ (0-9) +. [0-9] * [1-9] [0-9] *) | ([0-9] * [1-9] [0-9] *. [0-9] +) | ([0-9] * [1-9] [0-9] *)) $

19 floating point number: ^ (-?\ d +) (\.\ d +)? $or ^ -? ([1-9]\ d *.\ d * | 0.\ d * [1-9]\ d * | 0?\ .0 + | 0) $

Second, the expression of check characters

1 Chinese character: ^ [\ u4e00 -\ u9fa5] {0,} $

2 English and numbers: ^ [A-Za-z0-9] + $or ^ [A-Za-z0-9] {4jue 40} $

3 all characters with a length of 3-20: ^. {3pm 20} $

4 A string of 26 letters: ^ [A-Za-z] + $

5 A string of 26 uppercase letters: ^ [Amurz] + $

6 A string of 26 lowercase letters: ^ [amurz] + $

7 A string of numbers and 26 letters: ^ [A-Za-z0-9] + $

8 A string of numbers, 26 letters, or underscores: ^\ w {3pm 20} $or ^\ w

9 Chinese, English, numbers including underscore: ^ [\ u4E00 -\ u9FA5A-Za-z0-9] + $

10 symbols in Chinese, English, numbers but excluding underscores: ^ [\ u4E00 -\ u9FA5A-Za-z0-9] + $or ^ [\ u4E00 -\ u9FA5A-Za-z0-9] {2heroin 20} $

11 you can enter characters such as ^% &',; =? $\ ": [^% &',; =? $\ x22] + 12 forbids the input of characters containing ~: [^ ~\ x22] +

III. Expression of special requirements

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

Domain name: [a-zA-Z0-9] [- a-zA-Z0-9] {0a-zA-Z0 62} (/. [a-zA-Z0-9] [- a-zA-Z0-9] {0jue 62}) + /.?

3 InternetURL: [a-zA-z] +: / / [^\ s] * or ^ http://([\w-]+\.)+[\w-]+(/[\w-./?%&=]*)?$

4 Mobile number: ^ (13 [0-9] | 14 [5 | 7] | 15 [0 | 1 | 2 | 3 | 5 | 6 | 7 | 8 | 9] | 18 [0 | 1 | 2 | 3 | 5 | 6 | 7 | 8 | 9])\ d {8} $

5 phone numbers ("XXX-XXXXXXX", "XXXX-XXXXXXXX", "XXX-XXXXXXX", "XXX-XXXXXXXX", "XXXXXXX" and "XXXXXXXX"): ^ (\ (\ d {3pc4} -) |\ d {3.4} -)?\ d {7pc8} $

6 domestic telephone number (0511-4405222, 021-87888822):\ d {3} -\ d {8} |\ d {4} -\ d {7}

7 ID number (15 digits, 18 digits): ^\ d {15} |\ d {18} $

8 short ID card number (ending with a number and letter x): ^ ([0-9]) {7Magne 18} (x | X)? $or ^\ d {8jue 18} | [0-9x] {8pr 18} | [0-9X] {8jue 18}? $

9 whether the account is legal (at the beginning of the letter, 5-16 bytes are allowed, and alphanumeric underscores are allowed): ^ [a-zA-Z] [a-zA-Z0-9 _] {4j 15} $

10 password (begins with a letter, is between 6 and 18 in length, and can only contain letters, numbers and underscores): ^ [a-zA-Z]\ w {5je 17} $

Strong 11 passwords (must contain a combination of uppercase and lowercase letters and numbers, cannot use special characters, length between 8 and 10): ^ (? =. *\ d) (? =. * [Amurz]) (? =. * [Amurz]). {8jue 10} $

12 date format: ^\ d {4} -\ d {1pr 2} -\ d {1pc2}

13 12 months of the year (01 / 09 and 01 / 12): ^ (0? [1-9] | 1 [0-2]) $

14 31 days of a month (01 / 09 and 01 / 31): ^ (0? [1-9]) | (1 | 2) [0-9]) | 30 | 31) $

The input format of 15 money:

16 1. There are four forms of money we can accept: "10000.00" and "10000.00", and "10000" and "10000" without "points": ^ [1-9] [0-9] * $

17 2. This means any number that does not start with 0, but it also means that a character "0" does not pass, so we take the following form: ^ (0 | [1-9] [0-9] *) $

18 3. A 0 or a number that does not start with 0. We can also allow a negative sign at the beginning: ^ (0 | -? [1-9] [0-9] *) $

19 4. This represents a 0 or a number that may be negative and begins with a non-zero. Let the user start with 0. Get rid of the negative sign, too, because the money can't be negative. What we want to add next is the possible decimal part: ^ [0-9] + (. [0-9] +)? $

20 5. It must be noted that there should be at least 1 digit after the decimal point, so "10." No, but "10" and "10.2" are passed: ^ [0-9] + (. [0-9] {2})? $

21 6. In this way, we stipulate that there must be two digits after the decimal point. If you think it is too harsh, you can go like this: ^ [0-9] + (. [0-9] {1mem2})? $

22 7. This allows the user to write only one decimal place. Now it's time for us to consider the comma in the number. We can go like this: ^ [0-9] {1 # 3} (, [0-9] {3}) * (. [0-9] {1 # 2})? $

23 8.1 to 3 digits, followed by any comma + 3 digits, the comma becomes optional instead of having to: ^ ([0-9] + | [0-9] {1 ~ 3} (, [0-9] {3}) *) (. [0-9] {1 ~ 2})? $

24 Note: this is the end result. Don't forget that "+" can be replaced with "*" if you think an empty string is acceptable (strange, why?) Finally, don't forget to remove the backslash when using the function. The usual mistakes are here.

25 xml file: ^ ([a-zA-Z] + -?) + [a-zA-Z0-9] +\. [X | X] [m | M] [l | L] $

26 regular expressions for Chinese characters: [\ u4e00 -\ u9fa5]

27 double-byte characters: [^\ X00 -\ xff] (including Chinese characters, can be used to calculate the length of a string (a double-byte character length meter 2))

28 regular expression for blank lines:\ n\ s*\ r (can be used to delete blank lines)

29 regular expression of HTML tags:] * >. *? | (the version circulated on the Internet is too bad, the above one is only partial, and there is nothing I can do about complex nested tags.)

30 regular expressions for white space characters: ^\ s* |\ sblank $or (^\ s*) | (\ sblank $) (which can be used to delete white space characters at the beginning and end of a line (including spaces, tabs, page feeds, etc.), a very useful expression)

31 Tencent QQ number: [1-9] [0-9] {4,} (Tencent QQ number starts from 10000)

32 China Postal Code: [1-9]\ d {5} (?!\ d) (China Postal Code is 6 digits)

33 IP address:\ d +\.\ d +\.\ d + (useful when extracting IP addresses)

34 IP address: (?: 25 [0-5] | 2 [0-4]\ d | [01]?\\ d?\\ d)\\.) {3} (?: 25 [0-5] | 2 [0-4]\ d | [01]?\ d?\\ d)

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