Thread: PL/PGSQL Regexe

I'm doing a check within a PL/PGSQL function using a regular expression 
and I get the error:

ERROR:  regcomp failed with error invalid character range

This appears to be because of the underscore "_" character. The regex I 
want to use is ''[A-Za-z0-9_]'' but this doesn't work. Any suggestions 
or is this a bug/feature?