Question

targetOne : header/headerAB.h source/sourceA.cpp source/sourceB.cpp source/main.cpp
         g++ -Wall header/headerAB.h source/sourceA.cpp source/sourceB.cpp source/main.cpp

Is there a reason why I should break this in multiple targets rather then keeping it as one?
In what cases do we need to have separate targets rather than one in a Makefile?

Answer 1

Citing http://mrbook.org/tutorials/make/

Using dependencies.
Sometimes is useful to use different targets. This is because if you modify a single file in your project, you don’t have to recompile everything, only what you modified.

So you will get faster recompilation after partial source update. And this is “must to implement” for huge projects, where any change is very small (comparing to entire > 1M LOC project).

Also, multiple targets allows you to set different rules for different parts of project.