using reference in formal parameter causes error,how to resolve it

shamjs · 09-28-2011, 08:26 AM

Hi all,
if i try to use reference in formal parameter the compiler is reporting error as
error: no matching function for call to âPREDICT::GetModelAverageQResidualContribution3D(TNT::Array3D<double>)â

note: candidates are: TNT::Array2D<double> PREDICT::GetModelAverageQResidualContribution3D(TNT::Array3D<double>&)

Here is my code which defines the function

Code:

Array2D<REAL> GetModelAverageQResidualContribution3D(Array3D<REAL> & )  
	{
//here i have some code that uses model_xresiduals but i wont modify it.
//Array2D , Array3D are all user defined
}

here is the code that i invoke the above function

Code:

cout << pred.GetModelAverageQResidualContribution3D(val.GetResiduals());

if i remove "&" i wont get error,but i need to make that formal parameter as an alias(to actual argument) , plz suggest me to do this...........
waiting for your reply

Mara · 09-28-2011, 12:27 PM

From the error message and the code it seems that you try to pass double to a code that is compiled for the REAL type (possibly float?). If the size of the floating point data is different in different parts of the code, it may be a good idea to make conversion.

dwhitney67 · 09-28-2011, 04:21 PM

Quote:

Originally Posted by shamjs

Code:

cout << pred.GetModelAverageQResidualContribution3D(val.GetResiduals());

Try something like:

Code:

TNT::Array3D<REAL> residuals = val.GetResiduals();

cout << pred.GetModelAverageQResidualContribution3D(residuals);

The other alternative is to redefine GetResiduals() to return a reference to a class data member of type TNT::Array3D<REAL>. Something like:

Code:

namespace TNT
{
   ...

   class Var
   {
   public:
      Array3D<REAL>& GetResiduals()
      {
         ...

         return myResiduals;
      }

   private:
      Array3D<REAL> myResiduals;
   };
}

ta0kira · 09-28-2011, 08:22 PM

The error is saying that it can't make a reference from what you're passing. That means it's probably an rvalue (rvalues don't have to have addresses); in this case, val.GetResiduals() probably returns Array3D<REAL> which can only be used for a const reference or be passed by value. If possible, have the function take a const reference.
Kevin Barry

shamjs · 09-29-2011, 04:59 AM

thanx for your suggestion ,it worked.....