I have wrote regular expression to accept following type of versions

• "a.." ---> any version of "a"
• "a.b.*" ---> any version of "a.b"
• "a.b " ---> "a.b" or later
• "a.b.c " ---> "a.b.c" or later

An example: "4.2.2 ", "4.3.*, "4.2 "

/^([0-9])\.([0-9] [*]{0,1}[ ]?)(?:\.([0-9] [*]{0,1}[ ]?))?$/

It is accepting above all type but also accepting "4.2 .0" which should be invalid. How can I avoid this "4.2 .0" scenario.

Can anyone provide me regex to validate above versions?

CodePudding user response：

Please use following regex for validating version /^\d ((?:.\d ([ ]$){0,1})|(.[*]{1,1})){1,2}$/

^ Start of string \d Match 1 digits

1. (?:.\d ([ ]$)) Repeat matching 1 or more times . and 1 digits if are you adding then $ End of string. OR
2. (?:.?[*])? Optionally match an optional dot * for one or two times $ End of string

Please check here

CodePudding user response：

To match the examples with at least a single dot and an optional * or at the end:

^\d (?:\.\d ) (?:\.?[ *])?$

• ^ Start of string
• \d Match 1 digits
• (?:\.\d ) Repeat matching 1 or more times . and 1 digits
• (?:\.?[ *])? Optionally match an optional dot and either * or
• $ End of string

See a regex demo.

To also match the examples without a dot you can change the plus to an asterix for the repeating group:

^\d (?:\.\d )*(?:\.?[ *])?$

See another regex demo.