Thread: Cutting out the middle man with stream writing

I'm trying to use output streams to output biunary data, with some of that data being private class variables. I'm atrying to code it in a way where I can cut out having to copy the values to local variables before doing so, because it might be more efficient

This is the only way I know that works:

Code:

class A {
private:
	int _x;
public:
	void setX(int val) { _x = val; }
	int x() { return _x; }
};

int main()
{
	A a;
	a.setX(89);
	int x = a.x(); // trying to see if I can avoid making this copy
	file.write(reinterpret_cast<const char*>(&x), sizeof(int));
	return 0;
}

I've tried numerous things without success:
- returning int & doesn't work like this: char * p = reinterpret_cast<char*>(a.x()) because C++ interprets it as a value for some reason
- returning const int * doesn't work either

Is the only way to do this to make a wrapper function of some sort, expose the private vars, or copy them to local vars?

How about:

Code:

const int&  x() const { return _x; }

Code:

file.write(reinterpret_cast<const char*>(&a.x()), sizeof(int));

That would work, no?

Add a write_x function to A.

Originally Posted by Guest

How about:

Code:

const int&  x() const { return _x; }

Code:

file.write(reinterpret_cast<const char*>(&a.x()), sizeof(int));

That would work, no?

It does! Thanks!

Originally Posted by Chris87

It does! Thanks!

I wonder if that's still making an implicit copy.