Compiling C++ code stored in a Ruby string without writing it into a file

Question

I'm writing a Ruby code which generates a string containing a C++ program. For instance the Ruby string may contain:

#include <iostream>
using namespace std;int main(){cout<<"Hello World"<<endl;return 0;}

In order to run the C++ program stored in the Ruby string, I write the string into a file named c_prog.cpp, then use:

%x( g++ c_prog.cpp -o output )

to compile the C++ program in the file, then use:

value = %x( ./output )

and then print the value.

Since the C++ program stored in the Ruby string is very long (thousands of LOC), writing it to the file wastes some time. Is there any way I can compile the program stored in the string without writing it into a file? I mean something like:

%x( g++ 'the ruby string' -o output )

instead of:

%x( g++ c_prog.cpp -o output )

Community · Accepted Answer · 2017-05-23 11:58:34Z

3

You can pass in a single dash as a file name to tell g++ to read from STDIN. So,

%x( echo 'the ruby string' | g++ -o output -x c++ - )

should do the trick. See this related question.

edited May 23, 2017 at 11:58

CommunityBot

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answered Jun 4, 2015 at 7:52

Max

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TartanLlama · Accepted Answer · 2015-06-04 07:59:52Z

2

You can use the PTY library to pipe directly in to the g++ process:

require 'pty'

m, s = PTY.open
r, w = IO.pipe
pid = spawn("g++ -o output -x c++ -", :in=>r, :out=>s)
r.close
s.close
w.puts "#include <iostream>\n int main(){std::cout << \"Hello World\" << std::endl;}"
w.close

answered Jun 4, 2015 at 7:59

TartanLlama

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