[texhax] \input{file} adds an extraneous space

[Heiko Oberdiek]

On Tue, Jan 03, 2012 at 01:53:57AM -0800, jtzzaa11-texhax2 at yahoo.com wrote:

> I've noticed that \input{file} adds an extraneous space, for example, if
> f.tex contains abc
> 
> then
> \input{f}test
> 
> produces 
> abc test
> 
> Here is a minimal example:
> \documentclass[10pt]{article}
> \begin{document}
> \input{f}test
> \end{document}

The space is correct.
If TeX reads a line, it removes the end line marker and spaces
at the end of the line. Then it inserts the character, configured
by \endlinechar. Usually it's <CR> (0x13) with catcode end of line (5)
that then becomes a space.

Rationale. Without space the previous paragraph would read like
  The space is correct.If TeX ... and spacesat the end ... configuredby ...

> Would appreciate suggestions how to solve this.

If you don't want that space at the line end, one solution is
already shown. A comment char at the line end puts the
inserted end of line character in a comment:
  abc%
But that means, the contents of the file needs to be modified.
Another way is to set
  \endlinechar=-1
during the reading of the input file. Then the insertion of
the end of line chararacter is suppressed, e.g.:

\begingroup
  \endlinechar=-1 %
  \input{f}%
\endgroup
test

If the contents of the file should be put in a macro, then
package catchfile helps.

Yours sincerely
  Heiko Oberdiek