Essential Regular Expressions for Common Data Validation

Numeric Validation Patterns

Regular expressions for matching various numeric formats:

Any number of digits: ^[0-9]*$ Exactly n digits: ^\d{n}$ At least n digits: ^\d{n,}$ m to n digits: ^\d{m,n}$ Zero or non‑zero leading number: ^(0|[1-9][0-9]*)$ Non‑zero integer (max 2‑digit decimal): ^([1-9][0-9]*)+(\.[0-9]{1,2})?$ Signed number with optional 1‑2 decimal places: ^(\-)?\d+(\.\d{1,2})?$ Signed or unsigned number with optional decimal: ^(\-|\+)?\d+(\.\d+)?$ Positive real number with exactly two decimals: ^[0-9]+(\.[0-9]{2})?$ Positive real number 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 point: ^\d+(\.\d+)?$ or ^[1-9]\d*\.\d*|0\.\d*[1-9]\d*|0?\.0+|0$ Non‑positive floating point: ^((\-\d+(\.\d+)?)|(0+(\.0+)?))$ or ^(-([1-9]\d*\.\d*|0\.\d*[1-9]\d*))|0?\.0+|0$ General floating point (signed): ^(-?\d+)(\.\d+)?$ or

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

Character Validation Patterns

Regular expressions for validating various character sets:

Chinese characters (any length): ^[\u4e00-\u9fa5]{0,}$ Alphanumeric (letters and digits): ^[A-Za-z0-9]+$ or ^[A-Za-z0-9]{4,40}$ Any characters 3‑20 length: ^.{3,20}$ Only letters (A‑Z, a‑z): ^[A-Za-z]+$ Only uppercase letters: ^[A-Z]+$ Only lowercase letters: ^[a-z]+$ Alphanumeric (letters and digits): ^[A-Za-z0-9]+$ Alphanumeric with underscore: ^\w+$ or ^\w{3,20}$ Chinese, alphanumeric and underscore: ^[\u4E00-\u9FA5A-Za-z0-9_]+$ Chinese, alphanumeric without underscore: ^[\u4E00-\u9FA5A-Za-z0-9]+$ or ^[\u4E00-\u9FA5A-Za-z0-9]{2,20}$ Specific punctuation set: ^[%&',;=?$\"]+$ Exclude specific punctuation: [^%&',;=?$\x22]+ Exclude tilde:

[^~\x22]+

Special Requirement Patterns

Regular expressions for common special formats:

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})+/.?

URL (generic): [a-zA-z]+://[^\s]* or ^http://([\w-]+\.)+[\w-]+(/[\w-./?%&=]*)?$ Mobile phone (China): ^(13[0-9]|14[5|7]|15[0-9]|18[0-9])\d{8}$ Telephone (various formats): ^(\(\d{3,4}-)|\d{3.4}-)?\d{7,8}$ Landline (e.g., 0511-4405222): \d{3}-\d{8}|\d{4}-\d{7} Identity card (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}?$ Username (letter start, 5‑16 chars, letters/digits/underscore): ^[a-zA-Z][a-zA-Z0-9_]{4,15}$ Password (letter start, 6‑18 chars, letters/digits/underscore): ^[a-zA-Z]\w{5,17}$ Strong password (8‑10 chars, must include upper, lower, digit): ^(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{8,10}$ Date (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)$

Month (01‑12 or 1‑12): ^(0?[1-9]|1[0-2])$ Day of month (01‑31): ^((0?[1-9])|((1|2)[0-9])|30|31)$ Money amount (allow commas, optional 1‑2 decimal places): ^[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 shortcut: [\u4e00-\u9fa5] Full‑width character range: [\uFF00-\uFFFF] Half‑width character range: [\u0000-\u00FF] Blank line removal: \n\s*\r HTML tag matching (simplified): <(\S?)[^>]>.*?(?</\1>|<.*?/>) Trim leading/trailing whitespace: ^\s|\s$ QQ number (starts at 10000): [1-9][0-9]{4,} Chinese postal code (6 digits): [1-9]\d{5}(?!\d) IPv4 address (basic): \d+\.\d+\.\d+\.\d+ IPv4 address (validated):

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

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))

CSS property extraction: ^\s*[a-zA-Z\-]+\s*[:]{1}\s[a-zA-Z0-9\s.#]+[;]{1} HTML comment extraction: <!--(.*?)--> Image source extraction: \\< *[img][^\\>]*[src] *= *[\"\']{0,1}([^\"\'\ >]*) Hex color code: ^#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})$ File extension validation (txt): ^([a-zA-Z]\:|\\)\\([^\\]+\\)*[^\/:*?"<>|]+\.txt(l)?$ IE version detection (5‑8):

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

Notes

These patterns are intended as reference examples; they may need adaptation for specific programming languages or frameworks. Always test regexes with representative data to ensure correct behavior.