Question

Given a function that takes an output stringstream as an argument:

void Foo(const std::ostringstream& _oss);

Is there any way of writing the stream buffer to a file WITHOUT having to call str() ?

I want to avoid copying the buffer (which str() does).

void Foo(const std::ostringstream& _oss);
{
  std::ofstream f("foo.bin");

  //WANT: write _oss to f without copying the buffer?
}

Answer 1

There’s an operator<<() taking a stream buffer:

f << _oss.rdbuf();

However, the buffer needs to be really big for this to make a noticeable difference. Usually, writing to disk will dominate the time needed for this anyway.

Note that I’d avoid creating identifiers with leading underscores.