Comprehensive Collection of Regular Expressions for Validating Numbers, Characters, and Common Formats

1. Number Validation Regular Expressions

Simple digit string (any length): ^[0-9]*$

Exact n‑digit number: ^\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 leading number with up to two decimal places: ^([1-9][0-9]*)+(.[0-9]{1,2})?$

Positive or negative number with 1‑2 decimal places: ^(\-)?\d+(\.\d{1,2})?$

Signed number (optional +/‑) with optional decimal part: ^(\-|\+)?\d+(\.\d+)?$

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

Positive real number with 1‑3 decimal places: ^[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][]0-9"*$ or ^-\[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 ^[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 (optional sign): ^(-?\d+)(\.\d+)?$ or ^-?([1-9]\d*\.\d*|0\.\d*[1-9]\d*|0?\.0+|0)$

2. Character Validation Regular Expressions

Chinese characters (any length): ^[\u4e00-\u9fa5]{0,}$

Alphanumeric (letters and digits): ^[A-Za-z0-9]+$ or ^[A-Za-z0-9]{4,40}$

Any characters with length 3‑20: ^.{3,20}$

Only uppercase letters: ^[A-Z]+$

Only lowercase letters: ^[a-z]+$

Alphanumeric string: ^[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}$

Allow specific punctuation characters: [^%&',;=?$\x22]+

Disallow tilde (~): [^~\x22]+

3. Special‑Purpose Regular 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|1|2|3|5|6|7|8|9]|18[0|1|2|3|5|6|7|8|9])\d{8}$

Telephone number (various 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 ending with optional x/X): ^([0-9]){7,18}(x|X)?$ or ^\d{8,18}|[0-9x]{8,18}|[0-9X]{8,18}?$

Account name (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 contain upper, lower, digit): ^(?=.*\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 format examples (various patterns): ^[1-9][0-9]*$ , ^(0|[1-9][0-9]*)$ , ^(0|-?[1-9][0-9]*)$ , ^[0-9]+(.[0-9]+)?$ , ^[0-9]+(.[0-9]{2})?$ , ^[0-9]+(.[0-9]{1,2})?$ , ^[0-9]{1,3}(,[0-9]{3})*(.[0-9]{1,2})?$ , ^([0-9]+|[0-9]{1,3}(,[0-9]{3})*)(.[0-9]{1,2})?$

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

Chinese character regex: [\u4e00-\u9fa5]

Double‑byte character (including Chinese): [^\x00-\xff]

Blank line regex: \n\s*\r

HTML tag regex: <(\S*?)[^>]*>.*?</\1>|<.*? />

Leading/trailing whitespace regex: ^\s*|\s*$ or (^\s*)|(\s*$)

QQ number (starts with non‑zero, at least 5 digits): [1-9][0-9]{4,}

Chinese postal code (6 digits, not starting with 0): [1-9]\d{5}(?!\d)

IP address (IPv4 simple): \d+\.\d+\.\d+\.\d+

IP address (IPv4 strict): ((?:(?:25[0-5]|2[0-4]\d|[01]?\d?\d)\.){3}(?:25[0-5]|2[0-4]\d|[01]?\d?\d))

IP‑v4 address word boundary version: \\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

IP‑v6 address validation: (([0-9a-fA-F]{1,4}:){7,7}[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))

Date validation (yyyy‑mm‑dd with leap year check): ^(?:(?!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)$

Extract HTML comments: <!--(.*?)-->

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

Extract page hyperlinks (example pattern): (<a\s*(?!.*\brel=)[^>]*)(href="https?:\/\/)((?!(?:(?:www\.)?'.implode('|(?:www\.)?', $follow_list).'))[^" rel="external nofollow" ]+)("((?!.*\brel=)[^>]*)(?:[^>]*)>)

Extract image URLs: \\< *[img][^\\>]*[src] *= *[\"\']{0,1}([^\"\'\ >]*)

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

File extension validation (example for .txt): ^([a-zA-Z]\:|\\)\\([^\\]+\\)*[^\/:*?"<>|]+\.txt(l)?$

IE version detection (MSIE 5‑8, not Trident 5‑9): ^.*MSIE [5-8](?:\.[0-9]+)?(?!.*Trident\/[5-9]\.0).*$