Why regular expression doesn't work with bracket?

https://learninghub.kx.com/forums/topic/why-regular-expression-doesnt-work-with-bracket

I have below codes. Why the regular expression doesn’t work with {2}? The last 2 lines should be 1b instead. How to make it work? Thanks.

 

"42" like "[0-9][0-9]"; // i.e. 1b
"42" like "[0-9]{2}"; // i.e. 0b 
"42" like "[0-9]{2,2}"; // i.e. 0b

 

kdb+ does not implement full regex.

https://code.kx.com/q/basics/regex/

It supports ? * ^

 

If you want full support you can use the C interface to bring in external libraries

 

The patterns used by like are not actual regular expressions, so they don’t support this {n} syntax. I think the naming is unfortunate.

Regular expressions in q | Basics | q and kdb+ documentation - Kdb+ and q documentation (kx.com)