Merge C++ files into a single source file

23
votes

I have a c++ project with multiple source files and multiple header files. I want to submit my project for a programming contest which requires a single source file. Is there an automated way of collapsing all the files into single .cpp file?

For example if I had a.cpp, a.h, b.cpp, b.h etc., I want to get a main.cpp which will compile and run successfully. If I did this manually, could I simply merge the header files and append the source files to each other? Are there gotchas with externs, include dependencies and forward declarations?

7
c++
Too all answers "avoiding" the question. I can't zip up my project because the online judge expects a single cpp file to compile and run. - aramadia
The solution is in changing the judge. The judge should care about finding a makefile and what to expect as an output from the makefile (say, the name of the executable). But of course, that's no comfort for you. - wilhelmtell
My proposal: Use a compiler option like /E for VC 2015 to execute only the pre-processor. How it works: Generate one .cpp file, which includes all .cpp files #include "a.cpp" #include "b.cpp" ... of your project (no .h files!). Then compile this single .cpp file with the /E option. The result (stdout) is a single .cpp file, which contains the whole project. That's not convenient and the output is not really a beauty. However, it works. - mdew

7 Answers

8
votes

I also needed this for a coding contest. Codingame to be precise. So I wrote a quick JavaScript script to do the trick. You can find it here: https://www.npmjs.com/package/codingame-cpp-merge

I used it in 1 live contest and one offline game and it never produced bad results. Feel free to suggest changes or make pull requests for it on github!

1
votes

In general, you cannot do this. Whilst you can happily paste the contents of header files to the locations of the corresponding #includes, you cannot, in general, simply concatenate source files. For starters, you may end up with naming clashes between things with file scope. And given that you will have copy-pasted header files (with class definitions, etc.) into each source file, you'll end up with classes defined multiple times.

There are much better solutions. As has been mentioned, why not simply zip up your entire project directory (after you've cleaned out auto-generated object files, etc.)? And if you really must have a single source file, then just write a single source file!

1
votes

well, this is possiable, I have seen many project combine source files to single .h and .c/.cpp, such as sqlite

but the code must have some limits, such as you should not have static global variable in one of your source codes.

there may not have a generic tool for combine sources.you should write one base on your code.

here is some examples

gaclib source pack tool

1
votes

The CIL utility is able to do this:

$TIGRESS_HOME/cilly --merge -c x1.c -o x1.o
$TIGRESS_HOME/cilly --merge -c x2.c -o x2.o
$TIGRESS_HOME/cilly --merge -c x3.c -o x4.o
$TIGRESS_HOME/cilly --merge  --keepmerged x1.o x2.o x3.o -o merged --mergedout=merged.c

Usage example taken from here. Read the documentation about CIL and its shortcomings here. A binary distribution for Mac OS X and Linux is provided with Tigress.

0
votes

I don't know of a tool that combines .cpp files together but I would just zip all of the files up together and send them over as a gzip file.

0
votes

I think the project with headers, sources files must be must nicer than the one with only one main file. Not only easier to work and read with but also they know you do good job at separating program's modules.

Due to your solution, I provide this format and I think you have to do hand-work:

// STL headers


// --- prototype
// monster.h

// prince.h

// --- implementation

int main() { 
// your main function
return 0;
}
-2
votes

If you choose to send an individual file rather than a compressed archive, such as a tarball or a zip file, there are probably a few things you should consider.

First, concatenate the files together as Thomas Matthews already mentioned. With a few changes, you can typically compile the one file. Remove the non-existent #include statements, such as the headers that have now been included.

You will also have to concatenate these files in their respective dependency order. That is, if a.cpp needs a class declared in b.hpp, then you will most likely need to concatenate in the order Thomas Matthews listed.

That being said, I think the best way to share code is via a public repository, such as GitHub.com or compressed archive.