You use regular expressions when creating custom fields. Here is a list of available options.
Characters
| Use | To match | NOT |
| [set] | Any character in that set | [^set] |
| [a-z] | Any character in the range a - z | [^a-z] |
| . | Any character, except newline | |
| \w | Word character | \W |
| \d | Decimal character | \D |
| \s | White space | \S |
| \char | Escaped special character |
Quantifiers, Anchors and Alternation
|
Quantifiers |
To match |
| * | 0 or more times |
| + | 1 or more times |
| ? | 0 or 1 time |
| {n} | Exactly n times |
| {n,m} | From n to m times |
|
Anchors |
To match |
| ^ | At the start of the string |
| \A | At the start of the string |
| \z | At the end of the string |
| $ | At the end of the string |
| \G | Where the previous match ended |
| \b | On the word boundary |
| \B | Not on the word boundary |
|
Alternation |
To match |
| a|b | a or b |
| (?{[exp, name]} yes | no) | Yes if the expression or name is matches, else no |
Examples
| ^\d+$ | Integers only |
| ^\w+$ | Alphanumeric characters |
| ^\$?\d+$ | US Dollars |
| ^\£?\d+$ | UK Pounds |
| ^((((0[13578])|([13578])|(1[02]))[\/](([1-9])|([0-2][0-9])|(3[01])))|(((0[469])|([469])|(11))[\/](([1-9])|([0-2][0-9])|(30)))|((2|02)[\/](([1-9])|([0-2][0-9]))))[\/]\d{4}$|^\d{4}$ | US Date |
| ^(((0?[1-9]|[12]\d|3[01])[\.\-\/](0?[13578]|1[02])[\.\-\/]((1[6-9]|[2-9]\d)?\d{2}))|((0?[1-9]|[12]\d|30)[\.\-\/](0?[13456789]|1[012])[\.\-\/]((1[6-9]|[2-9]\d)?\d{2}))|((0?[1-9]|1\d|2[0-8])[\.\-\/]0?2[\.\-\/]((1[6-9]|[2-9]\d)?\d{2}))|(29[\.\-\/]0?2[\.\-\/]((1[6-9]|[2-9]\d)?(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00)|00)))$ | UK Date, including leap year calculation |
Worked example
To explain a little more, if we break down the US date example like this:
| ^((((0[13578])|([13578])|(1[02])) |
If from the beginning ("^") the number is 01, 03, 05, 07, 08, 1, 3, 5, 7, 8, 10, 12 (or January, March, May, July, August, October December) |
| [\/] | After the backslash |
| (([1-9])|([0-2][0-9])|(3[01])))| | You can have any number between 1 and 31 |
| (((0[469])|([469])|(11)) | If the month is April, June, September or November |
| [\/] | After the backslash |
| (([1-9])|([0-2][0-9])|(30)))| | You can have any number between 1 and 30 |
| ((2|02) | If the month is February |
| [\/] | After the backslash |
| (([1-9])|([0-2][0-9])))) | You can have any number between 1 and 29 |
| [\/] | After the backslash |
| \d{4}$|^\d{4}$ | You have the year |
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