Regex searching for number and letter combination optional brackets -

i need regex find match of single lower case a-z character followed 5 numbers either:

• at start of line
• at end of line
• surrounded () or []
• surrounded whitespace

so following results expected:

a12345 match

(a12345) match

[a12345] match

text a12345 match

aa12345 no match

at moment have (?<=[])]*)[a-z]{1}[0-9]{5}(?=[])]*) not working scenarios, example sees aa12345 , a12345a being matches when don't want them to.

can help?

edit: apologies should have mentioned .net c#

first of should mention programming language.

following solution pcre.

regex: ((?<=[\[( ])|^)[a-z]\d{5}((?=[\]\) ])|$)

explanation:

1. ((?<=[\[( ])|^) checks preceding brackets, whitespaces or beginning.

2. [a-z]\d{5} checks alphabet followed 5 digits.

3. ((?=[\]\) ])|$) checks succeeding brackets, whitespaces or end of line.

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