C++: making a single file without includes

Question

This might sound like a very weird question, but I do need this: I have a bunch of c++ header files (from some header-only libraries) and a single cpp file. What I'd like to do is generate a single cpp file that has no includes whatsoever.

Why? For a contest, in which the compiler doesn't have some libraries I'm using, and one in which you can only submit one single cpp file.

Ideally, this "script" would create a file that uses only what is actually needed, not just copy and paste recursively all "#includes".

I'm sure that the preprocessor generates some files when you add an "#include" in the code. So, how can I see these intermediate and (probably very long) files?

Consult your compiler's reference manual. Most compilers allow you to write preprocessed output to disk. — IInspectable
– IInspectable, Commented Jan 14, 2016 at 3:27

Samir Aguiar · Accepted Answer · 2016-01-14 04:10:55Z

8

GCC provides the -E option, so it stops after preprocessing the files. The documentation has more options that can be applied to the preprocessor.
clang also accepts -E, as stated here.
Visual Studio provides the /P (Preprocess to a File) compiler switch. It instructs the compiler to:

Preprocess[es] C and C++ source files and write[s] the preprocessed output to a file.

The output is written to a file with a file name based on the source file with an .i extension. To specify a different file name, use the /Fi (Preprocess Output File Name) compiler switch.
Intel C++ Compiler will stop after preprocessing if you pass either the -E option (outputs to stdout) or -P (outputs to a file). On Windows these will be the /E and /P switches respectively. The manual has more information on this.

edited Jan 14, 2016 at 4:10

answered Jan 14, 2016 at 3:28

Samir Aguiar

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