Bypassing writing object file? (GCC, g++)

[Gladdok]

Hi I'm learning how to use GNU Compiler Collection to compile C++ projects.

Let's say I have a project with three source files:
main.cc
modulea.cc
modulea.hh

modulea defines a simple little std::cout function that is called from main().

I can build my executable like so:

$ g++ main.cc modulea.cc
$ ./a.out

and the result is a.out which I can execute.

I assume this is equivalent to creating an object file before compiling and using that:

$ g++ -c modulea.cc
$ g++ main.cc modulea.o
$ ./a.out

Same result, I get a.out.

Is the .o object file needed to help with using make to selectively re-compile only changed parts of the code?

[helios]

Yes. make compares timestamps of sources and object files to decide which files to update.

[Moschops]

As an aside, your terminology is a little confused - an object file is what you get when you compile. There's no way to bypass making an object file, only to avoid making it again if the source hasn't changed.

[Gladdok]

Thanks for the replies I think I understand more clearly now.

The reason I asked is because in the 1st example, there is no modulea.o file created that I can tell. Is it created temporarily and deleted once a.out is written?

[Moschops]

Is it created temporarily and deleted once a.out is written?

KaBingo.