invalid operands to binary expression error

Question

I'm trying to write a matrix program in C++ and I get the error invalid operands to binary expression. I know it has to do with my overloaded operator with "*". In my code main.cpp:

Matrix mat7=mat1*3;
cout<<"Mult m1 * 3;"<<endl;
print_matrix(mat7);

In this part I am multiplying matrix 1 by 3.

What I need help on is in my matrix.cpp

Matrix Matrix::operator * (const Matrix& mat2){
   if(this->num_cols==mat2.num_rows){
       Matrix result(num_rows, mat2.num_cols);
       for(int i=0; i<num_rows; i++){
           for(int j=0; j<mat2.num_cols; j++){
               result.matrix[i][j]=0;
               for(int k=0; k<this->num_cols; k++){
                   result.matrix[i][j]+=matrix[i][k]*mat2.matrix[k][j];
               }
           }
       }
       return result;
   }
   else{
       Matrix result(num_rows, num_cols);
       for(int i=0; i<num_rows; i++){
           for(int j=0; j<num_cols; j++){
               result.matrix[i][j]=0;
           }
       }
       return result;
   }
}

This for my multiplication operator overload to multiplying another matrix.

My question is how do I do the same but with an integer?

Answer 1

I think defining a method Matrix Matrix::operator* (int factor) should do what you're looking for.