Menu
I'd like a regex that is either X or Y characters long. For example, match a string that is either 8 or 11 characters long. I have currently implemented this like so: ^([0-9]{8}|[0-9]{11})$.
I could also implement it as: ^[0-9]{8}([0-9]{3})?$
My question is: Can I have this regex without duplicating the [0-9] part (which is more complex than this simple \d example)?
782
A regular expression (or RE) specifies a set of strings that matches it; the functions in this module let you check if a particular string matches a given regular expression (or if a given regular expression matches a particular string, which comes down to the same thing).
Regular expression matching can be simple and fast, using finite automata-based techniques that have been known for decades. In contrast, Perl, PCRE, Python, Ruby, Java, and many other languages have regular expression implementations based on recursive backtracking that are simple but can be excruciatingly slow.
A literal character or matching something literally refers to specifying an actual character in the text: for instance, a to match a , as opposed to a character class such as \w that could also match a .
There is one way:
^(?=[0-9]*$)(?:.{8}|.{11})$ or alternatively, if you want to do the length check first,
^(?=(?:.{8}|.{11})$)[0-9]*$ That way, you have the complicated part only once and a generic . for the length check.
Explanation:
^ # Start of string (?= # Assert that the following regex can be matched here: [0-9]* # any number of digits (and nothing but digits) $ # until end of string ) # (End of lookahead) (?: # Match either .{8} # 8 characters | # or .{11} # 11 characters ) # (End of alternation) $ # End of string If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
