[Nauty-list] malfunction of catg

Brendan McKay bdm at cs.anu.edu.au
Mon Mar 14 15:42:42 EST 2011

You are quite right and your fix is good.  Thanks for reporting it.

To everyone on the list: I'm gearing up for a major new release of
nauty so now would be a good time to report problems.

Cheers, Brendan.

* William Rummler <w.a.rummler at gmail.com> [110314 15:28]:
> > It seems that catg omits the first char of each file when concatenating
> > files. What's wrong?
> I checked this out and it appears to happen when catg is processing
> graph files without headers. Specifically, at the end of the
> openfile_head() function in catg.c, inside the else-clause located on
> line 82-83, the statement "ungetc(c,f);" should be added to avoid
> losing the first character of the first graph in a header-less graph
> file when it is checked for a header.
> You could add the "-h" flag to all your geng commands, or you could
> edit catg.c --- Basically, replace line 83:
>         head[0]='\0';
> with the following (including the brackets, since ungetc() will not be
> blocked in the else-clause otherwise):
>     {
>         head[0]='\0';
>         ungetc(c,f);
>     }
> and recompile catg.c (or more simply just use the command "make"
> within your nauty source directory).
> - William
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