🚀 go-pugleaf

In article <6725@vtserf.cc.vt.edu> gbol@rglnext.geol.vt.edu (Gregory Lampshire) writes:
>
>
>I want to set up a macro where the presence of an argument will be  
>significant, that is
>
>\newcommand\fig[3]{
>	\if <argument #1 is null> do this etc.
>	\else etc.
>	\fi
>}
>
>
>\fig{}{}{this is a phrase}
>
>is different from
>
>\fig{2}{3}{this is a phrase}
>
>
>
>How do I test to see if an argument is null?  I tried
>
>
>\csname the #1 \endcsname but that naturally didn't work since the  
>argument is not a counter, register etc..
>
>

I ran into the same problem some days ago.  Here's a piece of the
code that tests whether the first argument is empty or not:

   {\setbox0=\hbox{\ignorespaces#1\unskip\relax}%
    \ifdim \wd0=0pt%
       % do whatever you want if the argument is empty
    \else%
       % do whatever you want if it isn't
    \fi%
   }%

I'm not a TeXpert, but it works fine for me.

>
>
>--
>Gregory Lampshire 
>Virginia Tech NeXT CC
>Bradley Department of Electrical Engineering
>gbol@rglnext.geol.vt.edu (NeXTmail welcome)
>------------------------
>My opinions are my very own and do not reflect the opinions of any  
>employer


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wszczepo@mailhost.ecn.uoknor.edu
witold@eis.cs.tu-bs.de

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C:  A middle-level programming language which combines the power
    of assembly language with the readability of assembly language.