Returning vectors of vector

[Shruthi LS]

Hi all,

 std::vector<float> TEST()
    {
    std::vector<float> ws;
    std::vector<float> space;
    int count =0; 

    // Do stuffs

    
    }  
  return ws,space;
  }

How to return the ws and space in the above Function TEST. And I am calling the
function as:

v1,v2 = TEST();

If I check the result I am only getting the v2 vector. Both are overwriting.
How to rectify the above problem?

Thank you.

[MikeyBoy]

To return a vector of vectors, your return type should be:

std::vector<std::vector<float>>

If you find that syntax hard to read, you could make it clearer using typedefs, e.g.

typedef std::vector<float> FloatVector;

std::vector<FloatVector> TEST()
{
  std::vector<FloatVector> retVector;
  // ...

  return retVector;
}

If I check the result I am only getting the v2 vector. Both are overwriting.

Nothing is overwriting anything. The problem is that you are using the comma operator without understanding what it actually does.

[seeplus]

You can return the two vectors as a pair then extract when the function called. Consider:

#include <utility>
#include <vector>

auto TEST()
{
	std::vector<float> ws;
	std::vector<float> space;
	int count = 0;

	// Do stuffs


	return std::pair (ws, space);
}


int main()
{
	auto [v1, v3] = TEST();

	// use v1 and v2 as vector<float>
}

If you need to return more than 2 items then you could use std::tuple rather than std::pair.


PS You'll need at least C++17 for this to compile.