C++におけるコンストラクション関数、コピーコンストラクション、付与関数

#include<iostream>
using namespace std;
    class test
    {
    public:
/*                                 **************/
        test()
        {
        }

        test(int a,short id) 
        {
             this ->a  = a;     //this        ，  main()   t
             this ->id = id;
        }

        test(int a,short id,int sum):a(a),id(id),sum(sum +a +id)
        {
        }
/**************     ************************************/
     test(const test& sd)
     {
        this-> a = sd.a;
        this-> id = sd.id;
        this-> sum = sd.sum;
     }

     /*      **************************/
     test & operator = (const test& sd)
     {

        this-> a = sd.a;
        this-> id = sd.id;
        this-> sum = sd.sum;
        return *this;
     }
    public :
       void  show()
        {
            cout<<a<<endl;
            cout <<id<<endl;
            cout << sum <<endl;
        }
    private :
        int  a;
        short id;
        int sum;
    };
int main()
{
    test t(12,32);
    t.show();

    test t1(1,3,0);
    t1.show();

    test t2(t1);
    t2.show();

    test t3;
    t3.show();
    t3 = t2;
    t3.show();

    return 0;
}

#include<iostream>
using namespace std;
    class test
    {
    public:
/*                                 **************/
        test()
        {
        }

        test(int a,short id) 
        {
             this ->a  = a;     //this        ，  main()   t
             this ->id = id;
        }

        test(int a,short id,int sum):a(a),id(id),sum(sum +a +id)
        {
        }
/**************     ************************************/
     test(const test& sd)
     {
        this-> a = sd.a;
        this-> id = sd.id;
        this-> sum = sd.sum;
     }

     /*      **************************/
     test & operator = (const test& sd)
     {

        this-> a = sd.a;
        this-> id = sd.id;
        this-> sum = sd.sum;
        return *this;
     }
    public :
       void  show()
        {
            cout<<a<<endl;
            cout <<id<<endl;
            cout << sum <<endl;
        }
    private :
        int  a;
        short id;
        int sum;
    };
int main()
{
    test t(12,32);
    t.show();

    test t1(1,3,0);
    t1.show();

    test t2(t1);
    t2.show();

    test t3;
    t3.show();
    t3 = t2;
    t3.show();

    return 0;
}
12
32
-858993460
1
3
4
1
3
4
-858993460
-13108
-858993460
1
3
4
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