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Editor to share with you how to write regular expressions, I believe that most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's learn about it!

one。 Check number

Number: ^ [0-9] * $

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

At least n-digit number: ^\ d {n,} $

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

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

A number with up to two decimal places at the beginning of a non-zero: ^ ([1-9] [0-9] *) + (. [0-9] {1J2})? $

Positive or negative numbers with 1-2 decimal places: ^ (\ -)?\ d + (\. D {1jin2})? $

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

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

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

A positive integer that is not zero: ^ [1-9]\ dbath $

Non-zero negative integer: ^\-[1-9] [] 0-9 "* $

Non-negative integer: ^\ dBy $

Non-positive integer: ^-[1-9]\ d* | 0 $

Non-negative floating point number: ^\ d + (\.\ d +)? $

Non-positive floating point number: ^ ((-\ d + (\.\ d +)?) | (0 + (\ .0 +)?)) $

Positive floating point number: ^ [1-9] d.d | 0.d [1-9] d $

Negative floating point number: ^-([1-9]\ d *.\ d * | 0\.\ d * [1-9]\ d *) $

Floating point number: ^ (-?\ d +) (\.\ d +)? $

two。 Validated character

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

English and numbers: ^ [A-Za-z0-9] + $

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

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

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

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

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

A string consisting of numbers, 26 letters, or underscores: ^\ wicked $

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

Chinese, English, numbers but excluding underscores and other symbols: ^ [\ u4E00 -\ u9FA5A-Za-z0-9] + $

You can enter characters such as ^% &',; =? $\ ": [^% &',; =? $\ x22] +

Prohibited from entering characters containing ~: [^ ~\ x22] +

three。 Special requirements expression

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

Mobile number: ^ (13 [0-9] | 14 [5 | 7] | 15 [0 | 1 | 2 | 3 | 6 | 7 | 8 | 9] | 18 [0 | 1 | 2 | 5 | 6 | 7 | 8 | 9])\\ d {8} $(regular expressions of domestic mobile numbers starting with 13, 15 and 18, the first two digits can be expanded according to the current domestic collection number)

Phone numbers ("XXX-XXXXXXX", "XXXX-XXXXXXXX", "XXX-XXXXXXX", "XXX-XXXXXXXX", "XXXXXXX" and "XXXXXXXX"): ^ (\ (\ d {3Magin4} -) |\ d {3.4} -)?\ d {7pc8} $

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

ID card number (15 digits): ^ [1-9]\\ d {7} ((0\\ d) | (1 [0-2])) (([0 | 1 | 2]\\ d) | 3 [0-1])\\ d {3} $

ID card number (18 digits): ^ [1-9]\\ d {5} [1-9]\\ d {3} ((0\\ d) | (1 [0-2])) ([0 | 1 | 2]\\ d) | 3 [0-1])\\ d {3} ([0-9] | X) $

Whether the account is legal (starting with letters, allowing 5-16 bytes, allowing alphanumeric underscores): ^ [a-zA-Z] [a-zA-Z0-9 _] {4jue 15} $

Password (begins with a letter, is between 6 and 18 in length, and can only contain letters, numbers and underscores): ^ [a-zA-Z]\ w {5Magne17} $

Strong password (must contain a combination of uppercase and lowercase letters and numbers, cannot use special characters, length is between 8 and 16): ^ (? =. *\ d) (? =. * [Amurz]) (? =. * [Amurz]). {8jue 16} $

Date format: ^\ d {4} -\ d {1pc2} -\ d {1pc2}

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

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

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

Regular expressions for Chinese characters: [\ u4e00 -\ u9fa5]

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)

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

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

Tencent QQ number: [1-9] [0-9] {4 QQ 11} (Tencent QQ number starts from 10000)

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

IP-v4 address:\\ b (?: 25 [0-5] | 2 [0-4] [0-9] | [01]? [0-9] [0-9]?)\\.) {3} (?: 25 [0-5] | 2 [0-4] [0-9] | [01]? [0-9] [0-9]?)\ b (useful when extracting IP addresses)

Verify IP-v6 address: ([0-9a-fA-F] {1 9a-fA-F 4}:) {7 9a-fA-F 7} [0-9a-fA-F] {1 4} | ([0-9a-fA-F] {1 9a-fA-F 4}:) {1 7}: ([0-9a-fA-F] {1 9a-fA-F 4}:) {1 6}: [0-9a-fA-F] {1 Piao 4} | ([0-9a-fA-F] {1 Person4}:) {1Pert 5} (: [0-9a-fA-F]) ] {1 9a-fA-F 4}) {1 9a-fA-F 2} | ([0-9a-fA-F] {1 9a-fA-F 4}:) {1 9a-fA-F 4} (: [0-9a-fA-F] {1 9a-fA-F 4}) {1 9a-fA-F 3} (: [0-9a-fA-F] {1 9a-fA-F 4}) {1 9a-fA-F 4} | ([0-9a-fA-F] {1 pm 4}:) {1 Mague 2} (: [0-9a-fA-F] {1 pm 4}) {1pm 4} | [0-9a-fA-F] {1 9a-fA-F 4}: (: [0-9a-fA-F] {1 9a-zA-Z 4}) {1 9a-zA-Z 6}) | (: [0-9a-zA-Z] {1 9a-zA-Z 4}) {1 9a-zA-Z 7} |:) | (: [0-9a-zA-Z] {0-9a-zA-Z] {1) | |:: (ffff (: 0 {0 9a-fA-F 4}) {0Power1}:) {0ffff 1} ((25 [0-5]) | (2 [0-4] | 1 {0Power1} [0-9]) {0Magne1} [0-9]) {0Magne1} (25 [0-5] | (2 [0-4] | 1 {0quotient 1} [0-9]) {0jin1} [0-9]) | ([0-0] 1}:) {1pm 4}: (25) [0-5] | (2 [0-4] | 1 {0rect 1} [0-9]) {0rect 1} [0-9])\\.) {3jue 3} (25 [0-5] | (2 [0-4] | 1 {0jue 1} [0-9]))

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

Verification date: ^ (?: (! 0000) [0-9] {4}-(: 0 [1-9] | 1 [0-2])-(: 0 [1-9] | 1 [0-9] | 2 [0-8]) | (?: 0 [13-9] | 1 [0-2])-(?: 29 | 30) | (?: 0 [13578] | 1 [02])-31) | (?: [0-9] {2} (?) [48] | [2468] [048] | [13579] [26]) | (?: 0 [48] | [2468] [048] | [13579] [26]) 00)-02-29) $(date check in "yyyy-mm-dd" format A flat leap year has been considered.)

Extract comments:

Find the CSS attribute: ^\\ s * [a-zA-Z\\ -] +\\ s * [:] {1}\\ s [a-zA-Z0-9\\ s.#] + [;] {1}

Extract page hyperlink: (] *) (href= "https?:\\ /\ /) ((?! (: (?): (?: www\.)?'. Implode ('| (?: www\\.)', $follow_list).)) [^" rel= "external nofollow"] +) "((?!. *\\ brel=) [^ >] *) (?: [^ >] *) >

Extract web page images:\

] * [src] * = * [\ "\'] {0reco1} ([^\\"\\'\ >] *)

Extract web page color code: ^ # ([A-Fa-f0-9] {6} | [A-Fa-f0-9] {3}) $

File extension validity: ^ ([a-zA-Z]\\: |\)\ ([^\] +\) * [^\ /: *? "|] +\ .txt (l)? $

Judge the IE version: ^. * MSIE [5-8] (?:\. [0-9] +)? (?!. * Trident\ / [5-9]\ .0). * $

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