🚀 go-pugleaf

I`d appreciate a lot if you could take the time to read the following
and perhaps even reply if you have an idea of what the problem might be:

I will have to develop some smaller C programmes  (some hundreds of
lines of code at the most) to run on a UNIX workstation.
I thought that for my needs, GCC looked like a good choice to write and
perhaps test those programmes on my Macintosh, which is just a Performa
400 (16 MHz 68030, no FPU) 6/40. I am using System D1-7.1P.
The programmes I have to write will perform some calculations. They read
their input from a file and write their output to another one, so I do
not even need screen output, which of course would be nice, but probably
rather difficult to implement on the Mac due to the lack of a standard
text line based interface. Or are there any solutions available? 

Not having the MPW, I obtained the standalone version of GCC found
at nic.switch.ch.
The most important problem I am facing right now is linking. It looks
like I do not understand the concept of suitcases.
For testing purposes, I have written the following little patch of
code:

#include <stdio.h>
void main(void)
{
FILE *fp;
if((fp=fopen("testfile","w"))!=NULL)
{
fputc((int)"a",fp);
fclose(fp);
}
}

which should create a file called "testfile" containing the character
"a".
Preprocessing, Compiling and Assembling went fine.
I have obtained the MPW headers and libraries from ftp.apple.com and
added the folders I keep them in in to the search path. Is that OK?

Now, when I try to link it, I get
Untitled.o: Undefined symbol _fopen referenced from text segment
Untitled.o: Undefined symbol _fputc referenced from text segment
Untitled.o: Undefined symbol _fclose referenced from text segment

What am I doing wrong??? (obviously these functions do not exist or
cannot be found?)

I made a second attempt, opening the stdio.suit suitcase that comes with
GCC before assembling. After assembling, I opened the DRVR entry in the
stdio.suit to find that my .o file had just been added in there. I then
selected all the entries in the DRVR window (maybe it would be better
just to select some entries, but I cannot select them except in a
contiguous range) and linked. I got dozens of errors like
wsetup.o: Undefined symbol _free referenced from text segment
vsscanf.o: Undefined symbol _strlen referenced from text segment
vfscanf.o: Undefined symbol __ctype_ referenced from text segment
just to quote the first ones. :-(((

How can I successfully link my programme???

Do I need the files from ftp.apple.com for that?
What are the files found in the archives gcc-1.37-includes.sit and
GCC_1.37.1r14_libsrc.sit which I also got from nic.switch.ch for?? Do I
need them for the sample programme above??

Any help would be greatly appreciated.
Thanks a lot!

(Yes, I did read all the help texts. Nevertheless, I do not have a clue
how to proceed.)