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Why regular expression doesn’t 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 -
2 Replies
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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
- https://code.kx.com/q/basics/regex/#regex-libraries
- https://code.kx.com/developer/libraries/regular-expression-pcre2/
- https://github.com/KxSystems/ffi/blob/master/examples/pcre.q
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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)
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