Compile time error in Eclipse, ld: symbol(s) not found for architecture x86_64

[KingOfSting]

I am programming in the IDE Eclipse, and have included a graphics engine, SDL. When I try to use commands included in the .h file for this engine, I get the following error:
ld: symbol(s) not found for architecture x86_64
Does anyone know how I can resolve this?
By the way, I am using a Mac, OS X 10.13.3.

[Peter87]

Are you linking the SDL library properly?

[KingOfSting]

Thank you for your reply.
I am pretty sure that I have linked it properly, as I followed the path in Terminal. I don't know what else to do, as I have tried everything. Do you have any other suggestions?

[Peter87]

Does it mention which symbols that can't be found?

[Peter87]

If you use SDL 1.2 you should try passing `sdl-config --cflags --libs` to the compiler.

If you use SDL 2.0 you should try `sdl2-config --cflags --libs` instead.