Mastering Common Regex Patterns for Data Validation

1. Number Validation Expressions

Digits: ^[0-9]*$ Exactly n digits: ^\d{n}$ At least n digits: ^\d{n,}$ m‑n digits: ^\d{m,n}$ Zero or non‑zero leading numbers: ^(0|[1-9][0-9]*)$ Non‑zero start with up to two decimal places: ^([1-9][0-9]*)+(\.[0-9]{1,2})?$ Positive/negative numbers with 1‑2 decimal places: ^(\-)?\d+(\.\d{1,2})?$ Signed numbers with optional decimals: ^(\-|\+)?\d+(\.\d+)?$ Positive real numbers with two decimals: ^[0-9]+(\.[0-9]{2})?$ Positive real numbers with 1‑3 decimals: ^[0-9]+(\.[0-9]{1,3})?$ Non‑zero positive integer: ^[1-9]\d*$ or ^([1-9][0-9]*){1,3}$ or ^\+?[1-9][0-9]*$ Non‑zero negative integer: ^\-[1-9]\d*$ Non‑negative integer: ^\d+$ or ^[1-9]\d*|0$ Non‑positive integer: ^-?[1-9]\d*|0$ or ^((\-\d+)|(0+))$ Non‑negative floating number: ^\d+(\.\d+)?$ or complex form ^[1-9]\d*\.\d*|0\.\d*[1-9]\d*|0?\.0+|0$ Non‑positive floating number: ^((\-\d+(\.\d+)?)|(0+(\.0+)?))$ or ^(-([1-9]\d*\.\d*|0\.\d*[1-9]\d*))|0?\.0+|0$ Positive floating 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]*))$

Negative floating 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]*)))$

General floating number: ^(-?\d+)(\.\d+)?$ or

^-?([1-9]\d*\.\d*|0\.\d*[1-9]\d*|0?\.0+|0)$

2. Character Validation Expressions

Chinese characters: ^[\u4e00-\u9fa5]{0,}$ Alphanumeric: ^[A-Za-z0-9]+$ or ^[A-Za-z0-9]{4,40}$ Any characters length 3‑20: ^.{3,20}$ Only letters: ^[A-Za-z]+$ Only uppercase letters: ^[A-Z]+$ Only lowercase letters: ^[a-z]+$ Alphanumeric only: ^[A-Za-z0-9]+$ Alphanumeric with underscore: ^\w+$ or ^\w{3,20} Chinese, English, digits, underscore: ^[\u4E00-\u9FA5A-Za-z0-9_]+$ Chinese, English, digits (no underscore): ^[\u4E00-\u9FA5A-Za-z0-9]+$ or ^[\u4E00-\u9FA5A-Za-z0-9]{2,20}$ Exclude specific symbols: [^%&',;=?$\x22]+ Exclude tilde:

[^~\x22]+

3. Special Requirement Expressions

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

[a-zA-Z0-9][-a-zA-Z0-9]{0,62}(/.[a-zA-Z0-9][-a-zA-Z0-9]{0,62})+/.?

Internet URL: [a-zA-z]+://[^\s]* or ^http://([\w-]+\.)+[\w-]+(/[\w-./?%&=]*)?$ Mobile phone number (China): ^(13[0-9]|14[5|7]|15[0-9]|18[0-9])\d{8}$ Telephone number formats: ^(\(\d{3,4}-)|\d{3.4}-)?\d{7,8}$ Domestic telephone (e.g., 0511-4405222): \d{3}-\d{8}|\d{4}-\d{7} Identity card number (15 or 18 digits): ^\d{15}|\d{18}$ Short ID (digits, optional trailing x): ^([0-9]){7,18}(x|X)?$ or ^\d{8,18}|[0-9x]{8,18}|[0-9X]{8,18}?$ Account name (starts with letter, 5‑16 chars, letters/digits/underscore): ^[a-zA-Z][a-zA-Z0-9_]{4,15}$ Password (starts with letter, 6‑18 chars, letters/digits/underscore): ^[a-zA-Z]\w{5,17}$ Strong password (8‑10 chars, includes upper, lower, digit, no special chars): ^(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{8,10}$ Date format (yyyy‑mm‑dd): ^\d{4}-\d{1,2}-\d{1,2} Month (01‑12): ^(0?[1-9]|1[0-2])$ Day of month (01‑31): ^((0?[1-9])|((1|2)[0-9])|30|31)$ Money formats (allow commas and up to two decimals): ^[0-9]{1,3}(,[0-9]{3})*(\.[0-9]{1,2})?$ or ^([0-9]+|[0-9]{1,3}(,[0-9]{3})*)(\.[0-9]{1,2})?$ XML file name: ^([a-zA-Z]+-?)+[a-zA-Z0-9]+\.[xX][mM][lL]$ Chinese character regex: [\u4e00-\u9fa5] Double‑byte character: ^\x00-\xff Blank line removal: \n\s*\r HTML tag regex (simplified): <(\S?)[^>]>.*?</\1>|<.*? /> Trim leading/trailing whitespace: ^\s|\s$ QQ number (starts from 10000): [1-9][0-9]{4,} Chinese postal code (6 digits): [1-9]\d{5}(?!\d) IPv4 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

IPv6 address:

(([0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|:((:[0-9a-fA-F]{1,4}){1,7}|:)|fe80:(:[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(ffff(:0{1,4}){0,1}:){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[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))

Full date validation (yyyy‑mm‑dd, leap year aware):

^(?:(?!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}(?:0[48]|[2468][048]|[13579][26])|(?:0[48]|[2468][048]|[13579][26])00)-02-29)$