仅限于大写或小写字母

Question

I have this regular expression

^(?:0[0-9]|1[0-3])-ARID-[0-9]{3}$

but it matches only strings like 10-ARID-278 but I want to that it should accept strings like 10-arid-257 too.

And not the strings like 10-Arid-257 or 10-ARid-257

The literal should be either ARID or arid , not the mix of upper and lower-case.

Answer 1

Explicitly list both uppercase and lowercase word, combining them using | (meaning OR).

^(?:0[0-9]|1[0-3])-(?:ARID|arid)-[0-9]{3}$