CODEWITHSUNDEEP
c++matrix
nadia
nadia

Reputation: 5

overloading operator (<<) cout in c++ is not working when i Subtract two matrix from each other

I am trying to subtract two matrices and print them in this format cout << (mat1 - mat2 ) << endl ; but the cout is not working, it works when i print one matrix and this is the code i don't think that i should make another cout operator for that 

#include <iostream>
#include <iomanip>
      using namespace std;

         struct matrix {
            int** data;
             int row, col;
          };

      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];
          } ;


 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] << " " ;
        }
        cout << endl ;
       }
    return out ;
};

this is the function for subtracing 

      matrix operator-  (matrix mat1, matrix mat2) {
             matrix  mattt  ;
           if (mat1.row == mat2.row && mat1.col == mat2.col) {

               for (int i =0 ; i< mat1.row ; i++) {
                     for (int j =0 ; j < mat1.col ; j++) {
                     mattt.data[i][j] = ((mat1.data [i][j]) - (mat2.data [i][j]))  ;
               }
        }
   }

      else {
      cout  << " the matrixs dont have the same dimensions " << endl ;
 }
    return mattt ;

 };


   int main()  {
     int data1 [] = {1,2,3,4,5,6,7,8};
      int data2 [] = {13,233,3,4,5,6};
      int data3 [] = {10,100,10,100,10,100,10,100};

    matrix mat1, mat2, mat3;
    createMatrix (4, 2, data1, mat1);
    createMatrix (2, 3, data2, mat2);
    createMatrix (4, 2, data3, mat3);

     cout << mat1 << endl;
     cout << mat2 << endl;
     cout << mat3 << endl;

     cout << ( mat3 - mat1 ) << endl ;
   };

Upvotes: 0

Views: 100

Answers (1)

Bathsheba
Bathsheba

Reputation: 234725

The function parameter list for the overloaded << operator needs to be changed to

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

Note well the const.

Otherwise the anonymous temporary (mat3 - mat1) cannot bind to the overload.

Upvotes: 6

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