How to ask, programmatically, a compiler to compile a file in C++?

Question

The following is my C++ program:

main.cpp

#include <iostream>
#include <fstream>

using namespace std;

int main() {

    ofstream fileWriter;
    fileWriter.open ("firstFile.cpp");
    fileWriter << "#include <iostream>" << endl;
    fileWriter << "int main() {" << endl;
    fileWriter << "\tstd::cout << \"hello world\" << std::endl;" << endl;
    fileWriter << "\treturn 0;" << endl;
    fileWriter << "}" << endl;
    fileWriter.close();

    return 0;
}

When the above program is executed, it creates a text-file named "firstFile.cpp" containing the following code:

firstFile.cpp

#include <iostream>
int main() {
    std::cout << "hello world" << std::endl;
    return 0;
}

which, when executed, prints "hello world" on the screen.

So, I would like to add to the main.cpp file lines of code asking GCC to compile the new firstFile.cpp just created.

I am using GNU gcc on both platform Ubuntu and Windows.

Is it possible to get any error code form the call to the compiler? If not why.

Answer 1

This is not too difficult using the std::system command. Also raw string literals allow us to insert multiline text which is useful for typing in program parts:

#include <cstdlib>
#include <fstream>

// Use raw string literal for easy coding
auto prog = R"~(

#include <iostream>

int main()
{
    std::cout << "Hello World!" << '\n';
}

)~"; // raw string literal stops here

int main()
{
    // save program to disk
    std::ofstream("prog.cpp") << prog;

    std::system("g++ -o prog prog.cpp"); // compile
    std::system("./prog"); // run
}

Output:

Hello World!

Answer 2

gcc is an executable, so you have to use either system("gcc myfile.cpp") or popen("gcc myfile.cpp"), which gives you a filestream as result.

But since you are generating code anyways, you don't even need to write it to a file. You can open the gcc proces with FILE* f = popen("gcc -x ++ <whatever flags>"). Then you have you can write your code with fwrite(f, "<c++ code>"). I know this is c and not really c++ but it might be useful. ( I don't think there is a c++ version of popen()).

Answer 3

All you need to do is add the following line after you create your file.

system("g++ firstFile.cpp -o hello");

Works on OS X so I hope it will work for you too.

Answer 4

To use the command line of a compiler in source file use system function.

Syntax of which is :

int system (const char* command); //built in function of g++ compiler.

In your case, it should be like

system("g++ firstFile.cpp");

PS: system function does not throw Exceptions.

Program

#include <iostream>
#include <fstream>
#include <cstdlib>

using namespace std;

int main() {

    ofstream fileWriter;
    fileWriter.open ("firstFile.cpp");
    fileWriter << "#include <iostream>" << endl;
    fileWriter << "int main() {" << endl;
    fileWriter << "\tstd::cout << \"hello world\" << std::endl;" << endl;
    fileWriter << "\treturn 0;" << endl;
    fileWriter << "}" << endl;
    fileWriter.close();

    system("g++ firstFile.cpp");

    return 0;
}