Is there a more succinct way to include a file based on a macro defining part of its name?

Question

Based on the user-defined numeric macro PROBNO, I want to include a file "prob[PROBNO].hpp", and run the function of the same name, prob[PROBNO](). The problem here is that I need the quotes around the included file, as < > gives me a file not found error. I'm currently doing the following:

#define STRINGIFY2(x)#x
#define STRINGIFY(x)STRINGIFY2(x)
#define CONCAT2(x,y)x##y
#define CONCAT(x,y)CONCAT2(x,y)
#define PROBNAME CONCAT(prob,PROBNO)
#include STRINGIFY(PROBNAME.hpp)
#include<iostream>
int main(){
    std::cout<<PROBNAME()<<'\n';
}

This does the job, but it looks messy. is there any way I can get rid of some of the directives somehow?

You don't need token concatenation to produce a filepath, and using concatenation can result in (unnecessary) compiler errors. Not using concatenation will simplify your macros. See http://stackoverflow.com/a/32077478/1566221 for an example and more explanation. — rici, Feb 06 '16 at 20:29

score 1 · Answer 1 · answered Feb 06 '16 at 19:01

1

Use angles instead of quotes:

#define PROBNAME <prob PROBNO.h>

#include PROBNAME

answered Feb 06 '16 at 19:01

Cecilio Pardo

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that gives a "file not found" error on my compiler, as it only uses < > for stdlib. – tomatopipps Feb 06 '16 at 19:17
Angles will end up searching on the same directories as quotes. If will also search on std directories, but after checking that, will check the same directories. Did you actually check it? Is the file name constructed correctly? – Cecilio Pardo Feb 06 '16 at 19:23
unless of course you are using a compiler that doesn´t :) – Cecilio Pardo Feb 06 '16 at 19:26
I tried just inputting the included file manually, and it works with quotes, but not angles. – tomatopipps Feb 06 '16 at 19:28
Then you could try setting include directories with your build tool. If not possible, then no luck with this approach. – Cecilio Pardo Feb 06 '16 at 19:31

Is there a more succinct way to include a file based on a macro defining part of its name?

1 Answers1