I've been stuck on this problem for days. I need a regex to validate an Id of this format:
^[0-9]{2}[-]{0,1}[0-9]{7}$
But from this pattern I have to exclude sets like:
- 00-0000000 and 000000000
- 11-1111111 and 111111111
- 22-2222222 and 222222222
- ...
- 99-9999999 and 999999999
Note that 22-2222221 is valid.
Can anyone help me? If the Id is written without the dash, I could use ^(\d)(?!\1{8})\d{8}$ but what if the hyphen is present?
Tried something like
^(\d)(?!\1{8})\d{8}$|^(\d)(?!\1{2})\d{1}-(?!\1{7})\d{7}$
but the second part does not seem to work properly.
Thanks to Wiktor for the solution. How would you adapt it also for pattern below?
^[0-9]{3}[-]{0,1}[0-9]{2}[-]{0,1}[0-9]{4}$
Probably something like this can work: ^(?!(\d)(?:-?\1)*$)\d{3}-?\d{2}-?\d{4}$
CodePudding user response：
You can use
^(?!(\d)(?:-?\1)*$)\d{2}-?\d{7}$
See the regex demo.
Details:
^- start of string(?!(\d)(?:-?\1)*$)- a negative lookahead that fails the match if there is(\d)- a digit (captured in Group 1)(?:-?\1)*- zero or more sequences of an optional-and then the digit that was captured in Group 2$- end of string, immediately to the right of the current location
\d{2}-?\d{7}- two digits, an optional-, and then seven digits$- end of string.
CodePudding user response：
To create a regular expression (regex) that matches a string that does not contain a repeated number with an optional hyphen, you can use the following regex:
^(?!.(\d)\1)[\d-]$
This regex uses a negative lookahead assertion to check if the string does not contain a repeated digit. The (?!.(\d)\1) part of the regex uses a capturing group ((\d)) to capture a digit, and then uses the backreference \1 to match the same digit again. The . before the negative lookahead assertion allows the regex to match any characters before the repeated digit, so the repetition can be detected even if it is not immediately adjacent.
The [\d-]* part of the regex allows the string to contain any number of digits or hyphens. The ^ and $ anchors at the beginning and end of the regex ensure that the entire string must match the pattern.
Here are some examples of how this regex can be used:
import re
Test strings that should match the regex
assert re.fullmatch(r'^(?!.(\d)\1)[\d-]$', '123-45-6789') is not None # Valid SSN assert re.fullmatch(r'^(?!.(\d)\1)[\d-]$', '9876-543-21') is not None # Valid SSN assert re.fullmatch(r'^(?!.(\d)\1)[\d-]$', '123456789') is not None # Valid SSN assert re.fullmatch(r'^(?!.(\d)\1)[\d-]$', '987654321') is not None # Valid SSN
Test strings that should not match the regex
assert re.fullmatch(r'^(?!.(\d)\1)[\d-]$', '123-45-6789-') is None # Invalid SSN assert re.fullmatch(r'^(?!.(\d)\1)[\d-]$', '123--45-6789') is None # Invalid SSN assert re.fullmatch(r'^(?!.(\d)\1)[\d-]$', '123-45-6789-0') is None # Invalid SSN assert re.fullmatch(r'^(?!.(\d)\1)[\d-]$', '123-45-6789-00') is None # Invalid SSN assert re.fullmatch(r'^(?!.(\d)\1)[\d-]$', '123-45-6789-000') is None # Invalid SSN