How to read a file at compile time in C++?

Question

I have been trying to look for a way to store files as const char* at compile time.

I tried doing this:

#define STRINGIFY(...) #__VA_ARGS__ // va args deals with commas
#define INCLUDE(path) #include path // error: '#' is not followed by a macro parameter

constexpr const char* source = STRINGIFY(INCLUDE("source.txt"));

but unfortunately you can't place include directives inside a macro expansion. Is there any way around this problem? Or any other way to get the contents of a file at compile time?

In particular, you appear to be looking for this [solution](https://stackoverflow.com/a/26161526/8372853). — cigien, Jun 14 '20 at 21:47

score 1 · Accepted Answer · answered Jun 14 '20 at 21:46

1

the classic way to do this is to write an awk or perl script that reads the data file and generates a .H file

answered Jun 14 '20 at 21:46

pm100

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thanks, the only thing is that if I want to change the file dynamically I would have to run the script again. – MaximV Jun 14 '20 at 22:03
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so you make it a build dependency – pm100 Jun 14 '20 at 22:08
which would you recommend between perl and awk for this kind of situation? – MaximV Jun 14 '20 at 22:29
hmm, perl probably – pm100 Jun 14 '20 at 22:39
And I would suppose that python might not be suitable for this? – MaximV Jun 14 '20 at 22:41
python works too, it is the 21st century after all. But everybody needs to have written at least one thing in perl – pm100 Jun 14 '20 at 22:43

How to read a file at compile time in C++?

1 Answers1