On Fri, Dec 26, 2008 at 7:16 AM, troels knak-nielsen <<a href="mailto:troelskn@gmail.com">troelskn@gmail.com</a>> wrote: <div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> I had a similar problem a few months back. Have a look over here: <a href="http://stackoverflow.com/questions/105816/how-do-i-access-a-char-through-ffi-in-plt-scheme" target="_blank">http://stackoverflow.com/questions/105816/how-do-i-access-a-char-through-ffi-in-plt-scheme</a></blockquote> <div> Figures, the exact question I was asking was already asked - typical. The answer doesn't really make sense to me. But, it gives me a place to start, and I'll mull it over from there. Oh - and I have the same goals you had when you were working on the code mentioned in the above post. It's all about learning FFI... Thanks, Ben  </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> -- troels <div><div></div><div class="Wj3C7c"> On Fri, Dec 26, 2008 at 12:44 AM, Ben Simon <<a href="mailto:benjisimon@gmail.com">benjisimon@gmail.com</a>> wrote: > Howdy - > > Now that my MySQL FFI implementation doesn't crash every few moments, I've > been able to make some headway into making the API useful.  This has been > going well, until I hit the row handling MySQL requires. Here's the C > example they provide: > > > MYSQL_ROW row; > unsigned int num_fields; > unsigned int i; > > num_fields = mysql_num_fields(result); > while ((row = mysql_fetch_row(result))) > { >    unsigned long *lengths; >    lengths = mysql_fetch_lengths(result); >    for(i = 0; i < num_fields; i++) >    { >        printf("[%.*s] ", (int) lengths[i], >               row[i] ? row[i] : "NULL"); >    } >    printf("\n"); > } > > Apparently, when I call mysql_fetch_row(...) it will return back a big array > of character data that is the series of columns.  I can index into this > array by calling mysql_num_fields and mysql_fetch_lengths. > > mysql_fetch_lengths returns back  an array of numbers, while the row object > is essentially an array. > > Given this, I think I need to focus on how Scheme handles C arrays.  What's > the cleanest way to handle this?   I've found some discussion about > cvectors, is that I'm looking for? > > Thanks, > -Ben > > -- > Have an idea for software?  I can make it happen - > <a href="http://www.ideas2executables.com" target="_blank">http://www.ideas2executables.com</a> > My Blog: <a href="http://benjisimon.blogspot.com" target="_blank">http://benjisimon.blogspot.com</a> > </div></div>> _________________________________________________ >  For list-related administrative tasks: >  <a href="http://list.cs.brown.edu/mailman/listinfo/plt-scheme" target="_blank">http://list.cs.brown.edu/mailman/listinfo/plt-scheme</a> > > </blockquote></div> -- Have an idea for software?  I can make it happen - <a href="http://www.ideas2executables.com">http://www.ideas2executables.com</a> My Blog: <a href="http://benjisimon.blogspot.com">http://benjisimon.blogspot.com</a>