matrix

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

class matrix {                  //////////////
private:                        //  a   b   //
    int a,b,c,d;                //  c   d   //
public:                         //////////////
    matrix(void);
    matrix(int,int,int,int);
    matrix(const matrix&);
    int det(void);                        ////    ///    ///           ///  /////////      /////////
    void show(const char[255]="\b");     /////    ///    ///          ///  ///     ///    ///     ///
    void operator=(const matrix&);      // ///    ///    ///         ///   ///     ///    ///     ///
    matrix operator+(matrix);          //  ///    ///    ///        ///    ///     ///    ///     ///
    matrix operator*(matrix);              ///    //////////       ///      /////////      /////////
    void operator+=(matrix);               ///           ///      ///       /////////      /////////
    void operator*=(matrix);               ///           ///     ///       ///     ///    ///     ///
    matrix operator-(void);                ///           ///    ///        ///     ///    ///     ///
    matrix operator-(matrix);              ///           ///   ///         ///     ///    ///     ///
    void operator-=(matrix);             ///////         ///  ///           /////////      /////////
};
void matrix::operator -=(matrix A) {
    (*this)=(*this)-A;
}

void matrix::operator *=(matrix A) {
    (*this)=(*this)*A;
}

void matrix::operator +=(matrix A) {
    (*this)=(*this)+A;
}

matrix matrix::operator*(matrix A) {
    return matrix(a*A.a+b*A.c, a*A.b+b*A.d, c*A.a+d*A.c, c*A.b+d*A.d);
}

matrix matrix::operator-(matrix A) {
    return -A+(*this);
}

matrix matrix::operator-(void) {
    return matrix(-a,-b,-c,-d);
}

matrix matrix::operator+(matrix A) {
    return matrix(a+A.a,b+A.b,c+A.c,d+A.d);
}

void matrix::operator =(const matrix& A) {
    a=A.a; b=A.b; c=A.c; d=A.d;
}

matrix::matrix() {
    a=1; b=0; c=0; d=1;
}

matrix::matrix(int a1, int b1, int c1, int d1) {
    a=a1; b=b1; c=c1; d=d1;
}

matrix::matrix(const matrix &A) {
    a=A.a; b=A.b; c=A.c; d=A.d;
}

int matrix::det() {
    return a*d-b*c;
}

void matrix::show(const char str[255]) {
    cout<<"Matrix "<<str<<":"<<endl;
    cout<<setw(5)<<a<<setw(5)<<b<<endl;
    cout<<setw(5)<<c<<setw(5)<<d<<endl<<endl;
}

int main() {
    matrix A(1,2,3,4),B(4,5,6,7),C;
    A.show("A");
    B.show("B");
    C.show("C");
    C=A*B;
    C.show("C=A*B");
    cout<<"Det[A]: "<<A.det()<<endl;
    cout<<"Det[B]: "<<B.det()<<endl;
    cout<<"Det[C]: "<<C.det()<<endl;
}