Check digit expressions

• Digit:

  ^[0-9]*$

• N digits:

  ^\d{n}$

• At least N digits:

  ^\d{n,}$

• m-n digits:

  ^\d{m,n}$

• Zero and non-zero start digits:

  ^(0|[1-9][0-9]*)$

• Nonzero number with up to two decimal places:

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

• A positive or negative number with one or two decimal places:

  ^(\-)?\d+(\.\d{1,2})?$

• Positive, negative, and decimals:

  ^(\-|\+)?\d+(\.\d+)?$

• A positive real number with two decimal places:

  ^[0-9]+(.[0-9]{2})?$

• A positive real number with 1 to 3 decimal places:

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

• A non-zero positive integer:

  ^[1-9]\d*$  or  ^([1-9][0-9]*){1,3}$  or  ^\+?[1-9][0-9]*$

• A non-zero negative integer:

  ^\-[1-9][]0-9"*$  or  ^-[1-9]\d*$

• Non-negative integers:

  ^\d+$  or  ^[1-9]\d*|0$

• Non-positive integer:

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

• Non-negative floating-point numbers:

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

• Non-positive floating-point number:

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

• 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]*))$

• Negative Float:

  ^-([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 number:

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

Check character expressions

• Alpha-Numeric Characters:

  ^[A-Za-z0-9]+$  or  ^[A-Za-z0-9]{4,40}$

• All characters with a length of 3-20:

  ^.{3,20}$

• A string of 26 letters:

  ^[A-Za-z]+$

• A string of 26 uppercase English letters:

  ^[A-Z]+$

• A string of 26 lowercase alphabetic characters:

  ^[a-z]+$

• A string of numbers and 26 letters:

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

• A string of numbers, 26 letters, or an underscore:

  ^\w+$  or  ^\w{3,20}$

• input with ^%&',;=?$\":

  [^%&',;=?$\x22]+

• It is forbidden to input characters with ~:

  [^~\x22]+

Special Needs Expressions

• Email:

  ^[a-zA-Z0-9_.+-][email protected][a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$

• URL or Domain name:

  ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?

• Date (MM/DD/YYYY)/(MM-DD-YYYY)/(MM.DD.YYYY)/(MM DD YYYY):

  ^(0?[1-9]|1[012])[- /.](0?[1-9]|[12][0-9]|3[01])[- /.](19|20)?[0-9]{2}$

• 12 months of the year(01~09 1~12):

  ^(0?[1-9]|1[0-2])$

• 31 days a month(01~09 1~31):

  ^(0[1-9]|[12][0-9]|3[01])$

• Password:

  ^.*(?=.{6,})(?=.*d)(?=.*[A-Z])(?=.*[a-z])(?=.*[[email protected]#$%^&*? ]).*$

• US Phone Numbers

  \b\d{3}[-.]?\d{3}[-.]?\d{4}\b

• US Zip code

  ^[0-9]{5}(?:-[0-9]{4})?$

• Slug

  ^[a-z0-9-]+$

• All the special characters need to be escaped

  /[\-\[\]\/\\\{\}\(\)\*\+\?\.\^\$\|]/

• xml file:

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

• Regular expressions for Chinese characters:

  [\u4e00-\u9fa5]

• Double-byte characters:

  [^\x00-\xff] 

• Blank line:

  \n\s*\r    (be used to delete blank lines)

• HTML tags:

  <(\S*?)[^>]*>.*?|<.*? />

• The leading and trailing whitespace character:

  ^\s*|\s*$ or (^\s*)|(\s*$)

• IP address:

  ((?:(?:25[0-5]|2[0-4]\d|((1\d{2})|([1-9]?\d)))\.){3}(?:25[0-5]|2[0-4]\d|((1\d{2})|([1-9]?\d))))