how to export function's result to text file in C++?

Question

 int main()
{
shape a;           //make class

ostream out;
out.open("test.txt");      // make file
out<< a.draw();           // std::ostream << void        error
                          // draw() { cout<<"ddd"<<endl; }
out.close();
}

I want to wirte draw() in to file. can you help me?

Use `#include` library, which is just a child class of iostream but for files. You would do `ofstream ofs("test.txt")` to create a file stream. — Francisco Gallego Salido, Dec 11 '17 at 10:11
Possible duplicate of [How to write std::string to file?](https://stackoverflow.com/questions/15388041/how-to-write-stdstring-to-file) — kenny_k, Dec 11 '17 at 10:23

score 0 · Answer 1 · answered Dec 11 '17 at 10:18

You have two options.

1: Pass the stream to the function and write to that instead of std::cout

void draw(std::ostream& os) { os << "ddd\n"; }

int main()
{
    std::ofstream s("test.txt");
    draw(s);
}

2: Return the result instead of writing it

std::string draw() { return "ddd\n"; }

int main()
{
    std::ofstream s("test.txt");
    s << draw();
}

how to export function's result to text file in C++?

1 Answers1