regex - Regular expression for a string that does not start with a sequence

I'm processing a bunch of tables using this program, but I need to ignore ones that start with the label "tbd_". So far I have something like [^tbd_] but that simply not match those characters.

Answer

You could use a negative look-ahead assertion:

^(?!tbd_).+

Or a negative look-behind assertion:

(^.{1,3}$|^.{4}(?

Or just plain old character sets and alternations:

^([^t]|t($|[^b]|b($|[^d]|d($|[^_])))).*