On Tue, Sep 13, 2016 at 12:54 PM, twilight <pipfstarrd at openmailbox.org> wrote: > c = cond(token, val, yylex(), noeval | !!a); !!foo converts the expression to 0 or 1. Since there's only one | here, it will set the low bit iff a != 0. Without it, it will or in whatever value a has, which may be wrong... Warner