About C/C++ compilation

When you have a set of files, you usually do 2 things:

• compile each source file (.c) to an object file (.o)
• link all object files into an executable.

The source files are independent - you need header files to be able to provide the "information" (declarations) about functions in a given module in order to let any other module use them. Header files are not compiled by themselves - they are #included as parts of source files.

Have a look below on how the commands for that look like and how they are handled by make.

About makefiles

Makefile is a set of targets and rules to build them. A target is "something which can be built and results in a given file". (There exist also "phony" targets which don't result in a file and just are there to execute commands - a common one is called clean to remove the compilation results).

Each target has 2 parts:

• list of dependencies, "sensitivity list" (other files and targets which are needed for this target) (after :, comma-separated),
• list of shell commands which are executed to build this target (below the above, indented)

Consider this example:

main: main.o module1.o module2.o
    g++ main.o module1.o module2.o -o main

This means that: "To build the file main, I need to first make sure that targets main.o, module1.o and module2.o are up to date; then I need to call the following command...".

This can be also rewritten as:

main: main.o module1.o module2.o
    gcc $^ -o $@

The variables (everything starting with $ is a variable) will be expanded to the dep