Wsrtjtyk

#include <iostream>





using namespace std;





class   matrix   



{



private:



    int row;



    int col;



    int **data;



public:



    matrix(int r=0,int c=0)



    {

        row=r;

        col=c;

        data=new int*[row];

        for(int i=0; i<row; i++)

        {

            data[i]=new int [col];

        }

    }



    friend void createMatrix (int row, int col, int num, matrix& mat);



    friend istream &operator>>(istream&in,matrix &mat);



    friend ostream &operator<<(ostream&out,matrix &mat);



    matrix operator+ (matrix mat)

    {

        matrix z(row,col);

        if((row==mat.row)&&(col==mat.col))

        {

            for(int i=0 ; i<row ; i++)

            {

                for(int j=0 ; j<col; j++)

                {

                    z.data[i][j]=data[i][j]+mat.data[i][j];

                }

            }

        }

        else

        {

            cout<<"Matrix that aren't the same size can't be added"<<endl;

        }

        return z;

    }        



};                   



 ostream &operator<<(ostream&out,matrix &mat)        



{



    for(int i=0; i<mat.row; i++)

    {

        for(int j=0; j<mat.col; j++)

        {

            out<<mat.data[i][j]<<" ";

        }

        out<<endl;

    }

    return out;

}



istream &operator >>(istream &in,matrix& mat)



{



    cout<<"Enter the size of your matrix"<<endl;

    in>>mat.row;

    in>>mat.col;

    mat.data=new int*[mat.row];

    cout<<"Enter the elements of your matrix"<<endl;

    for(int x=0; x<mat.row; x++)

    {

        mat.data[x]=new int[mat.col];

    }

    for(int i=0; i<mat.row; i++)

    {

        for(int j=0 ; j<mat.col; j++)

        {

            in>>mat.data[i][j];

        }

    }

    return in;

}



int main()



{



    matrix x,y;



    cin>>x>>y;

    cout<<x+y<<endl;

    return 0;

}



void createMatrix (int row, int col, int num, matrix& mat)



{



    mat.row = row;

    mat.col = col;

    mat.data = new int* [row];



    for (int i = 0; i < row; i++)

        mat.data[i] = new int [col];



    for (int i = 0; i < row; i++)

        for (int j = 0; j < col; j++)

            mat.data[i][j] = num[i * col + j];

}

When I try to run, I get the error:

|83|error: no match for 'operator<<' (operand types are 'std::ostream {aka std::basic_ostream<char>}' and 'matrix')|

but when I change the main to:

matrix x,y,z;

cin>>x>>y;

z=x+y;

cout<<z<<endl;

return 0;

I get no problems although I can't use that because I have to do about 14 different operator overloading I'm not sure if i'ts a code error or a compiler error. Any idea what I can do to solve it?

You have defined your operator<< to take a matrix reference

ostream &operator<<(ostream&out,matrix &mat)

while the output of the expression

x+y

is a temporary object that cannot be passed as a reference. You must either pass it as a const reference const matrix& mat or by value matrix mat. In this case, you should use a const reference, to avoid copying the whole matrix.

Use a const matrix:

ostream &operator<<(ostream&out,const matrix &mat)

This creates a temporary matrix

cout<<x+y<<endl;

It cannot be passed by ref only. And as it is for output, it should be const ref anyway.