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c++gcccompiler-errors
Kadaj13
Kadaj13

Reputation: 1541

Compilation error : No match for overloaded operator

here is a part of my code, when i compile it, it says 1: no match for operator = 2: no known conversion for argument 1 from 'Matrix' to 'Matrix&' but if i remove the operator + part it works where is the problem?! :|

gcc errors: "no match for 'operator=' in 'z = Matrix::operator+(Matrix&)((* & y))' candidate is: atrix& Matrix::operator=(Matrix&) no known conversion for argument 1 from 'Matrix' to 'Matrix&' "

class Matrix {
  //friend list:
  friend istream& operator>>(istream& in, Matrix& m);
  friend ostream& operator<<(ostream& in, Matrix& m);

  int** a;    //2D array pointer
  int R, C;   //num of rows and columns
  static int s1, s2, s3, s4, s5;
 public:
  Matrix();
  Matrix(const Matrix&);
  ~Matrix();
  static void log();

  Matrix operator+ (Matrix &M){
    if( R == M.R && C == M.C ){
        s4++;
        Matrix temp;
        temp.R = R;
        temp.C = C;         temp.a = new int*[R];
        for(int i=0; i<R; i++)
            temp.a[i] = new int[C];

        for(int i=0; i<R; i++)
            for(int j=0; j<C; j++)
                temp.a[i][j] = a[i][j] + M.a[i][j];

        return temp;
    }   
}

  Matrix& operator = (Matrix& M){
s5++;
if(a != NULL)
{
    for(int i=0; i<R; i++)
        delete [] a[i];
    delete a;
    a = NULL;
    R = 0;
    C = 0;
}
R = M.R;
C = M.C;
a = new int*[R];
for(int i=0; i<R; i++)
    a[i] = new int[C];

for(int i=0; i<R; i++)
    for(int j=0; j<C; j++)
        a[i][j] = M.a[i][j];    

return *this;
}

};

Upvotes: 1

Views: 597

Answers (1)

Bo Persson
Bo Persson

Reputation: 92241

Matrix operator+ (Matrix &M){
Matrix& operator= (Matrix &M){

They both share he same problem - the parameter type should be const Matrix& (just like in the copy constructor). Otherwise you cannot pass temporary objects to the operators.

Upvotes: 2

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