I am trying to get a regular expression that: - Has any sequence of 0 and 1. (Binary only) - And Does not contains 00
I know them separate but how I can combine them?
(?:[0-1]+)+
the above for sequence of 0101 of any kind.
Here is screenshot of the part of the question:
any clue reference would be appreciated.
I came to this form:
0?(1+0?)*
Explained:
0? - can start with 01+ - non-empty sequence of 1s0? - followed by at most one 0(1+0?)* - 2-3 repeated any number of times
00 . Demo: regex101.com/r/2CFroT/5
0, second 0 (and an empty string).Regular expressions such as 0?(1+0)* will match against any part of the string so it will match the middle part of a string such as 000011000000, it will match the 0110. To check that the whole string matches need to add the start and end of string anchors, giving ^0?(1+0)*$. This will also match an empty string. To match against a non-empty string we could use ^0?(1+0)+$ but this will not match a string with a single 0. So we need to add an alternative (using |) to match the 0, leading to the total expression ^((0?(1+0?)+)|0)$.
These brackets are capturing brackets, they could be changed to non-capturing forms but that would make the expression bigger and, visually, more complex.
