Regex, capture 4 numbers surrounded by . or line start/end

Question

I'm trying to capture any 1-2 digit numbers surrounded by '.' or the beginning/end of a line.

E.G

• 1.0.4.11

• 71.11.11.11

• 0.11.0.0

Are valid and:

• 1.
• 1111
• 11.11.11.
• 01.10

are not valid

Right now I've got (?<=\.|^)\d{1,2}]?(?=\.|$) which will capture the numbers correctly but will also capture groups such as 11.. or 1.11.

I need to extend this regex to basically verify that it is always in the format x.x.x.x where x is 1-2 digits.

For additional information, this regex will run using the wxWidgets regex class but I believe that's the standard regex parser.

NOTE

For anyone using this as reference... Using wxWidgets, the wxRegex class must be constructed with the wxRE_ADVANCEDflag as by default it uses a basic/fast implementation that does not include quantifiers(?*) which are used in this expression.

Answer 1

You can make it less generic by specifically look for your 4 groups between start and end of string (you can remove the \.? if you never have . at the start or end):

^\.?\d{1,2}\.\d{1,2}\.\d{1,2}\.\d{1,2}\.?$

See in Regex101