Question

I have to open files one by one for reading in C/C++. The name of the files are in0, in1, in2, in3…..
I tried to use preprocessor directive to create file names.
i want something like.

for(int i=0;i<n;i++)
{
    string inp_file="/path/"+"in"+APPEND(i);  //to generate /path/in1 etc
    open(inp_file);
}

where APPEND is a MACRO.
Since

#define APP(i) i

can generate the value

#define APP(i) #i

can convert a token to string.
I am trying to combine them both in many ways but failed.
How to get the desired result or is it even possible to get the such a result with macro?

Answer 1

Addendum to Vlad’s answer — if for some reason you’re not able/willing to use Boost, you can accomplish what you want using standard C++ with the stringstream class:

#include <sstream>

void Foo() {
    for (int i = 0; i < n; ++i) {
        std::stringstream converter;
        converter << "/path/in" << i;
        open(converter.str());
    }
}