Дополнительное задание 5 (дополнительная часть)

using namespace std;
template <typename T>
class Class_mat
{
protected:
    T a, b, c , d;
public:
    Class_mat()
    {
        a = 1;
        b = 2;
        c = 3;
        d = 4;
    };
    Class_mat(T x, T y, T z, T v)
    {
        a = x;
        b = y;
        c = z;
        d = v;
    };
    Class_mat ( const Class_mat &obj)
    {
        a = obj.a;
        b = obj.b;
        c = obj.c;
        d = obj.d;
    };
    Class_mat operator = (const Class_mat &obj)
    {
        a = obj.a;
        b = obj.b;
        c = obj.c;
        d = obj.d;
        return obj;
    };
    void det()
    {
        cout << "Определитель матрицы равен " << a * d - c * b;
    };
    //Перегруженный оператор *
Class_mat operator * (const Class_mat &obj) const
    {
        Class_mat a;
        a.a = this -> a * obj.a;
        a.b = this -> b * obj.b;
        a.c = this -> c * obj.c;
        a.d = this -> d * obj.d;
        return a;
    };

//Перегруженный оператор +
Class_mat operator + (const Class_mat &obj)
    {
        Class_mat a;
        a.a = this -> a + obj.a;
        a.b = this -> b + obj.b;
        a.c = this -> c + obj.c;
        a.d = this -> d + obj.d;
        return a;
    };

//Перегруженный оператор *=
Class_mat operator *= (const Class_mat &obj)
    {
        Class_mat a;
        a.a = this -> a *= obj.a;
        a.b = this -> b *= obj.b;
        a.c = this -> c *= obj.c;
        a.d = this -> d *= obj.d;
        return a;
    };

//Перегруженный оператор +=
Class_mat operator += (const Class_mat &obj)
    {
        Class_mat a;
        a.a = this -> a += obj.a;
        a.b = this -> b += obj.b;
        a.c = this -> c += obj.c;
        a.d = this -> d += obj.d;
        return a;
    };

//Перегруженный оператор *
Class_mat operator * (const T p) const
    {
        Class_mat a;
        a.a = this -> a * p;
        a.b = this -> b * p;
        a.c = this -> c * p;
        a.d = this -> d * p;
        return a;
    };

//Перегруженный оператор *=
Class_mat operator *= (const T p)
    {
        Class_mat a;
        a.a = this -> a *= p;
        a.b = this -> b *= p;
        a.c = this -> c *= p;
        a.d = this -> d *= p;
        return a;
    };

//Перегруженный оператор *
 friend Class_mat operator * (T p, const Class_mat &obj)
    {
        Class_mat a;
        a.a = p * obj.a;
        a.b = p * obj.b;
        a.c = p * obj.c;
        a.d = p * obj.d;
        return a;

    };
 friend std::ostream& operator<<(std::ostream &output, const Class_mat &obj)
 {
     output << "Коэффициент a = " << obj.a << endl << "Коэффициент b = " << obj.b << endl << "Коэффициент c = " << obj.c << endl << "Коэффициент d = " << obj.d << endl << endl;
     return output;
 };

~Class_mat ()
{
};
};