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October 2005

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2005.10.17 03:43 "newbie asks for help with mingw and libtiff", by <gnunes5@comcast.net>

2005.10.17 23:16 "Re: newbie asks for help with mingw and libtiff", by Frank Warmerdam

2005.10.17 03:43 "newbie asks for help with mingw and libtiff", by <gnunes5@comcast.net>

Hi-

I need a little help getting off the ground.  Below is what is supposed to
be my easy first attempt at using libtiff, but I cannot get it to
link...(this should be easy?)

/* file first.c */
#include <tiffio.h>
#include <stdio.h>

main()
{
  int w,h;

  TIFF* tif = TIFFOpen("foo.tif", "r");
  TIFFGetField(tif, TIFFTAG_IMAGEWIDTH, &w);
  TIFFGetField(tif, TIFFTAG_IMAGELENGTH, &h);
  TIFFClose(tif);
  printf("Width = %d\n", w);
  printf("Length = %d\n", h);
}

Here's what I did:

1.  Copied all the .h files and libraries from the libtiff default locations
to c:\mingw\include c:\mingw\lib, respectively.  (I know there is a right
way to point the mingw compile/link process at the files in their original
locations...please enlighten me!)

2. gcc -c first.c   This produces first.o, so I'm feeling pretty smug at
this point.

3. ld -o first first.0 c:\mingw\lib\libtiff.lib  (third argument could be
-ltiff)
This produces the following messages:

ld: warning: cannot find entry symbol _mainCRTStartup; defaulting to
00401000
first.o(.text+0x21):first.c: undefined reference to `_alloca'
first.o(.text+0x26):first.c: undefined reference to `__main'
first.o(.text+0x32):first.c: undefined reference to `printf'
first.o(.text+0x9b):first.c: undefined reference to `printf'
first.o(.text+0xae):first.c: undefined reference to `printf'

I know I am doing something simple and wrong.  I'm not new to programming,
but it's all Fortran or Labview.  I last did serious C back in grad school
(1e6 years ago).  I've only installed mingw so I can use libtiff, so my
problem is probably with using mingw rather than libtiff.  But if anyone can
take pity on me (I don't mind if you have a few chuckles at my expense!) I
would be very grateful.

-Geoff Nunes

P.S.  On a complete whim I tried 
ld -o first first.0 -lmsvcrt -ltiff and the three undefined references to
printf went away.  The rest of the messages remained.