Compile multiple C source fles into a unique object file

Question

I have some C source files and I am using gcc. I basically want to compile all of them and create one single object file. When I try:

gcc -c src         


        

Answer 1

To combine multiple source files into a single object file (at least since gcc 4.1), use the compiler/linker option --combine

(edit) later replaced with the compiler option -flto, with linking automatic depending on the compilation state: Requirements to use flto

Answer 2

You can't compile multiple source files into a single object file. An object file is the compiled result of a single source file and its headers (also known as a translation unit).

If you want to combine compiled files, it's usually combined into a static library using the ar command:

$ ar cr libfoo.a file1.o file2.o file3.o

You can then use this static library when linking, either passing it directly as an object file:

$ gcc file4.o libfoo.a -o myprogram

Or linking with it as a library with the -l flag

$ gcc file4.o -L. -lfoo -o myprogram

Answer 3

May be you're looking for this :

ld -r src1.o src2.o src3.o -o final.o

But its always nice to have them archived, using

ar rvs libmy.a file1.o file2.o file3.o

Then use -lmy to link.

Answer 4

You can always pipe the files to GCC:

join file1.c file2.c file3.c | gcc -x c -c -o single.o -

Don't forget the option specifying the language, "-x c", which now cannot be deduced from the file extension. You tell GCC to accept input from stdin with the single trailing dash "-".

Note that this is equivalent to compiling a file "final.c" with following contents:

#include "file1.c"
#include "file2.c"
#include "file3.c"

With

gcc -c -o single.o final.c

Answer 5

Either you make a final.c which will include all .c files then you can compile this final using gcc -c final.c command.

or

Another method is to use archive.Build all files to get respective .o then archive then in one library which will have all those .o file.

Answer 6

This is not a usual way to proceed, but you can easily achieve what you want by creating a new final.c file with the following content.

#include "src1.c"
#include "src2.c"
#include "src3.c"

Then you can compile it as follows.

gcc -c final.c -o final.o

Note that there may be issues, read compilation errors, even if each file compiles successfully when compiled separately. This tend to happen especially with macro definitions and includes, when merging your source files into a single one this way.