Regular Expression for String representing DNA code

Question

Hello I am trying to use regular expressions in a java program. I would like the regex to identify a String of unknown length and whose charachters are only \'C\', \'A\', \'G\'

Answer 1

Easy, just use a character class:

[CAGT]+

Or if the entire string has to comprise of the chars CAGT for it to match:

^[CAGT]+$

Answer 2

Adding to the above :

^[CAGTcagt]+$

To ensure detection of lowercase and upper case charcters.

Answer 3

I disagree with the most voted answer. With [ACGT]+, a large string will lead to a lot of memory usage. So I would use a negated regex instead, and check if the string doesn't contain non [ACGT] characters instead:

str !~ [^ACGTacgt]