How to write regexp which will validate the following strings?

Question

I have tried following regexp in cpp ^((T[X-Z]|R[X-Z])+?)(?:,\\s*|$). It validates only TX. If empty string it should be invalid, it should not accept numbers as well

User may enter:

1. TX
2. TX, TY
3. TX, TY, TZ,
4. RX, RY, RZ
5. RX

It should be valid in all cases.

Answer 1

For the test cases that you put here,([TR][XYZ])(,( )?)? might work.

I have tested it for you here (Mention that global and multiline flags are enabled)