Question

I want to try making a simple game engine. Just something that handles states, assets, characters/actors and their stats and an inventory. Most of the code I can take from other games I’ve wrote, but I’m confused on how I then turn it into a static library. Do I need a main.cpp? If so what has to go in it? Under Linux I’m guessing I compile it to .so and add the headers to my include directory and then just link to the .so but what do I do on Windows and Mac?

Answer 1

A .so is not a static library, it’s a dynamic one. A static library is, in its most basic, a .o file compiled from a single C file, or a .a file which is simply a collection of .o files.

A static library is different from a shared one in that the object code is linked directly in to the final executable, requiring no dependencies at run time.

Under Unix, the ar(1) command is used to bundle .o files in to a composite .a file. I do not know the comparable utility for Windows.

Once you have the .a file, you will simply need the combination of the .a file and the .h files to build your code. You use the .h files for compiling, and then link against the .a file.

Shared libraries have a specific advantage over static libraries in that if you have multiple, yet different, programs relying on the same libraries, the code from the shared libraries can be shared among all of the programs at the same time, so in that sense they lower the overall impact on the system. Their downside is slower start up times (though that’s pretty marginal nowadays). Statically linked libraries can not be shared across independent programs, but if you run the same executable several times, its code will be shared.