Why does C++ compilation take so long?

Question

Compiling a C++ file takes a very long time when compared to C# and Java. It takes significantly longer to compile a C++ file than it would to run a normal size Python script. I'm currently using VC++ but it's the same with any compiler. Why is this?

The two reasons I could think of were loading header files and running the preprocessor, but that doesn't seem like it should explain why it takes so long.

Answer 1

There are two issues I can think of that might be affecting the speed at which your programs in C++ are compiling.

POSSIBLE ISSUE #1 - COMPILING THE HEADER: (This may or may not have already been addressed by another answer or comment.) Microsoft Visual C++ (A.K.A. VC++) supports precompiled headers, which I highly recommend. When you create a new project and select the type of program you are making, a setup wizard window should appear on your screen. If you hit the “Next >” button at the bottom of it, the window will take you to a page that has several lists of features; make sure that the box next to the “Precompiled header” option is checked. (NOTE: This has been my experience with Win32 console applications in C++, but this may not be the case with all kinds of programs in C++.)

POSSIBLE ISSUE #2 - THE LOCATION BEING COMPILED TO: This summer, I took a programming course, and we had to store all of our projects on 8GB flash drives, as the computers in the lab we were using got wiped every night at midnight, which would have erased all of our work. If you are compiling to an external storage device for the sake of portability/security/etc., it can take a very long time (even with the precompiled headers that I mentioned above) for your program to compile, especially if it’s a fairly large program. My advice for you in this case would be to create and compile programs on the hard drive of the computer you’re using, and whenever you want/need to stop working on your project(s) for whatever reason, transfer them to your external storage device, and then click the “Safely Remove Hardware and Eject Media” icon, which should appear as a small flash drive behind a little green circle with a white check mark on it, to disconnect it.

I hope this helps you; let me know if it does! :)

Answer 2

Some reasons are:

1) C++ grammar is more complex than C# or Java and takes more time to parse.

2) (More important) C++ compiler produces machine code and does all optimizations during compilation. C# and Java go just half way and leave these steps to JIT.