[texhax] Why pdftex in dvi mode and in pdf mode works differently?

[Igor Liferenko]

Hi Philip,

Thanks for the explanation.

Until I received you response, I figured out the following:

In the following example "\def\a..." fails if \ifabc is false and
\myif is not initialized before "\def\a...".
In contrast, if \ifabc is true, \myif may be initialized before
or after "\def\a...".

\newif\ifabc
\abctrue % \abcfalse

%\let\myif=\iftrue

\ifabc
  \def\a#1#2{\myif#1\else#2\fi}
\fi

%\let\myif\iftrue

\ifabc
  \a{hello}{world}
\fi

\end

Thanks,
Igor