Most commonly used regular expressions

1. Expression of check digits

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1 Number: ^[0-9]*$
2 n-digit number: ^\d{n}$
3 A number of at least n digits: ^\d{n,}$
4 m-n digit number: ^\d{m,n}$
5 Numbers starting with zero and non-zero: ^(0|[1-9][0-9]*)$
6 Numbers starting with non-zero and with up to two decimal places: ^([1-9][0-9]*)+(.[0-9]{1,2})?$
7 Positive or negative numbers with 1-2 decimal places: ^(\-)?\d+(\.\d{1,2})?$
8 Positive numbers, negative numbers, and decimals: ^(\-|\+)?\d+(\.\d+)?$
9 Positive real numbers with two decimal places: ^[0-9]+(.[0-9]{2})?$
10 Positive real numbers with 1~3 decimal places: ^[0-9]+(.[0-9]{1,3})?$
11 Non-zero positive integer: ^[1-9]\d*$ or ^([1-9][0-9]*){1,3}$ or ^\+?[1-9][0 -9]*$
12 Non-zero negative integers: ^\-[1-9][]0-9"*$ or ^-[1-9]\d*$
13 Non-negative integers: ^\d+$ or ^[1-9]\d*|0$
14 Non-positive integers: ^-[1-9]\d*|0$ or ^((-\d+)|(0+))$
15 Non-negative floating point number: ^\d+(\.\d+)?$ or ^[1-9]\d*\.\d*|0\.\d*[1-9]\d*|0? \.0+|0$
16 Non-positive floating point number: ^((-\d+(\.\d+)?)|(0+(\.0+)?))$ or ^(-([1-9]\d*\.\ d*|0\.\d*[1-9]\d*))|0?\.0+|0$
17 Positive floating point 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]*))$
18 Negative floating point 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]*)))$
19 Floating point number: ^(-?\d+)(\.\d+)?$ or ^-?([1-9]\d*\.\d*|0\.\d*[1-9]\ d*|0?\.0+|0)$