Preferred compiler options for compiling/linking multiple files

[Colin Thomas]

Hi,

Up till now I have created single file code, but I need to compile multiple files as I have a large project

I would be interested in knowing what the prefered compiler options should be in this situation.

The following scenario might be a useful starting place.

      ###########################################

I have some global Variables, which are visible to each of the multiple files.

i.e. Global.h
///////////////////////////
#include <string>

string GlobalString;

#define GlobalREAD

///////////////////////////

In each of the mulitple files, I have

///////////////////////////
#ifndef GlobalREAD
 #include "Global.h"
#endif
///////////////////////////


Each multiple file is compiled as:

g++ -c -O2 -fno-strength-reduce -o  File1.o File1.cpp
g++ -c -O2 -fno-strength-reduce -o  File2.o File2.cpp
g++ -c -O2 -fno-strength-reduce -o  File3.o File3.cpp
.
.
.

Each compiles individually okay.

When I come to compile the final executable, pulling in File1.o/File2.o/File3.o using

g++ -o Final File1.o File2.o File3.o Final.cpp

I get errors like:

ld: fatal: symbol `GlobalString' is multiply defined:
        (file File1.o and file File2.o);

I know that the answer lies in one (of the many) compiler options, but an unsure of the ones for this case.

I am gcc 2.95.2 and on a sparc machine.

I look forward to being guided by your collective wisdom..

best regards

Colin Thomas ... EE not CS :-)