Mastering Regex: Essential Patterns for Numbers, Text, and Special Formats

Numeric Validation Expressions

Digits: ^[0-9]*$

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

At least n digits: ^\d{n,}$

m‑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})?$

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

Positive real number with 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]\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$

Positive floating point: ^[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 point: ^-([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]*)))$

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

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: ^[A-Za-z0-9]+$

Alphanumeric with underscore: ^\w+$ or ^\w{3,20}

Chinese, letters, digits, underscore: ^[\u4E00-\u9FA5A-Za-z0-9_]+$

Chinese, letters, digits (no underscore): ^[\u4E00-\u9FA5A-Za-z0-9]+$ or ^[\u4E00-\u9FA5A-Za-z0-9]{2,20}$

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

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

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}$

Phone number formats (e.g., "XXX-XXXXXXX"): ^(\(\d{3,4}-)|\d{3.4}-)?\d{7,8}$

Domestic phone (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 (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 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)$

Other

.*

matches any character except \n. /[\u4E00-\u9FA5]/ matches Chinese characters. /[\uFF00-\uFFFF]/ matches full‑width symbols. /[\u0000-\u00FF]/ matches half‑width symbols.

Money Input Formats

1. Accept four forms such as "10000.00", "10,000.00", "10000", "10,000": ^[1-9][0-9]*$ 2. Non‑zero leading number (zero alone allowed): ^(0|[1-9][0-9]*)$ 3. Optional leading minus sign: ^(0|-?[1-9][0-9]*)$ 4. Allow optional decimal part: ^[0-9]+(.[0-9]+)?$ 5. Require at least one digit after decimal: ^[0-9]+(.[0-9]{2})?$ 6. Allow one or two decimal digits: ^[0-9]+(.[0-9]{1,2})?$ 7. Allow commas as thousand separators: ^[0-9]{1,3}(,[0-9]{3})*(.[0-9]{1,2})?$ 8. Comma optional:

^([0-9]+|[0-9]{1,3}(,[0-9]{3})*)(.[0-9]{1,2})?$

Note: The final result can replace + with * if empty strings are acceptable; remember to remove the escaping backslash when using the pattern.

PS

https://www.runoob.com/regexp/regexp-tutorial.html

Online regex tester: http://tool.oschina.net/regex/