I want to match a section of a string that contains certain characters repeated, along with certain other characters only given a certain criteria. For instance matching characters a-z contained in angle brackets and numbers only if the number is preceeded by a plus.

Matching <abcde> to abcde.

<abcde1> should not match anything.

Matching <abcde 1> to abcde 1 Matching <abcde 1asd 2 3 4as> to abcde 1asd 2 3 4as

<abcde > should not match anything.

The regex I've tried is <([a-z]|(\ (?=[0-9])|[0-9](?<=[\ ])))*>.

CodePudding user response：

You can use

(?<=<)(?:[a-zA-Z] (?:\ \d )*) [a-zA-Z]*(?=>)
<((?:[a-zA-Z] (?:\ \d )*) [a-zA-Z]*)>

See the regex demo. Details:

• (?<=<) - a positive lookbehind that requires a < char immediately on the left
• (?:[a-zA-Z] (?:\ \d )*) - one or more occurrences of
  • [a-zA-Z] - one or more letters
  • (?:\ \d )* - zero or more sequences of and one or more digits
• [a-zA-Z]* - one or more ASCII letters
• (?=>) - a positive lookahead that requires a > char immediately on the right.