So, a question from a beginner. What is the .obj file that appears after the source is compiled into the executable? I can't find a good explanation on the Net for it. I take it the file has to accompany the executable for the program to function since the online explanations I've found say it contains instructions and is related to memory management? It's been bugging me from the start.

On Wednesday, 3 May 2017 at 10:55:44 UTC, I Lindström wrote:
> So, a question from a beginner. What is the .obj file that appears after the source is compiled into the executable? I can't find a good explanation on the Net for it. I take it the file has to accompany the executable for the program to function since the online explanations I've found say it contains instructions and is related to memory management? It's been bugging me from the start.

The source is not compiled into the executable. The source is compiled into a "object code", output into an "object file" - in this case, the .obj file. Afterwards, object files are linked by a linker (usually also taking other object files and/or libraries) to produce an executable or a library.
.obj files are not needed to be redistributed, they've served their purpose when the final target executable or library has been created. But it's useful to keep them in the development environment, as usually the build environment would not spend time recompiling the code when an up-to-date object files are present.

On Wednesday, 3 May 2017 at 11:09:33 UTC, Stanislav Blinov wrote:
>
> The source is not compiled into the executable. The source is compiled into a "object code", output into an "object file" - in this case, the .obj file. Afterwards, object files are linked by a linker (usually also taking other object files and/or libraries) to produce an executable or a library.
> .obj files are not needed to be redistributed, they've served their purpose when the final target executable or library has been created. But it's useful to keep them in the development environment, as usually the build environment would not spend time recompiling the code when an up-to-date object files are present.

Ohhhhhhhh... Many thanks. This cleared it for me. What happens at compile time is all magic to me still, but learning as I go.

Basically, .obj is a temporary file the compiler uses to store its half-finished work on the way to producing the exe.

Once you have the exe, the obj is no longer necessary, but keeping them around can sometimes speed up recompiles by reusing the left over work from last time. (Not so much in D though, this more applies to C.)