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

Question

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

User · Accepted Answer

You could use a negative look-ahead assertion:

^(?!tbd_).+

Or a negative look-behind assertion:

(^.{1,3}$|^.{4}(?<!tbd_).*)

Or just plain old character sets and alternations:

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

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

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