C++ copy constructor and assignment operator

assignable_class.cpp

class Assignable {
    private:
        int vPrivate = 0;
    public:
        int vPublic = 0;
       
        Assignable() {
            vPrivate = 0;
            vPublic = 0;
            cout << "Constructed()" << endl;
        }
       
        explicit Assignable(int _public) : vPublic(_public) {
            cout << "Constructed(int)" << endl;
        }
       
        void setPrivate(int _private) {
            vPrivate = _private;
        }
       
        void print() const {
            cout << vPublic << " " << vPrivate << endl;
        }
       
        Assignable& operator=( const Assignable& other ) {
            cout << "Called assignment operator" << endl;
            this->vPublic = other.vPublic;
            this->vPrivate = other.vPrivate;
            return *this;
        }
       
        Assignable(const Assignable &other) {
            cout << "called copy constructor" << endl;
            this->vPublic = other.vPublic;
            this->vPrivate = other.vPrivate;
        }
       
        ~Assignable() {
            cout << "destructed" << endl;
        }
};

assignop_assign.cpp

Assignable a1(5);
Assignable a2(10);
a1.setPrivate(5);
a2.setPrivate(10);
        
a2 = a1;
a2.print();

copycon_func_arg.cpp

cout << "Copy constructor call demo: when an instance of a class is passed "
                "as value to a function" << endl;
Assignable a1(5);
Assignable a2(10);
a1.setPrivate(5);
a2.setPrivate(10);

printAssignable(a1);

copycon_func_ret.cpp

cout << "Copy constructor call demo: when an instance of a class is "
        "returned by value " << endl;
Assignable a1 = giveMeNewClassNoopt(55, 55);
a1.print();
        
cout << endl << "Another flavor:" << endl;
Assignable a2 = giveMeNewClassOptimized(55, 55);
a2.print();
cout << "Don't be surprised if copy constructor is not called here. "
        "Compilers are known to optimize away this copy" << endl;

copycon_obj_cre.cpp

cout << "Copy constructor call demo: when a new instance of a class is "
        "created from an existing object" << endl;
Assignable a1(5);
a1.setPrivate(5);
Assignable a2(a1);
a2.print();
        
cout << endl << "Another flavor:" << endl;
Assignable a3 = a1;
a3.print();

cpcon_assignop_rough.cpp

#include <iostream>
 
using namespace std;
 
class Assignable {
    private:
        int vPrivate = 0;
    public:
        int vPublic = 0;
       
        Assignable() {
            vPrivate = 0;
            vPublic = 0;
            cout << "Constructed()" << endl;
        }
       
        explicit Assignable(int _public) : vPublic(_public) {
            cout << "Constructed(int)" << endl;
        }
       
        void setPrivate(int _private) {
            vPrivate = _private;
        }
       
        void print() const {
            cout << vPublic << " " << vPrivate << endl;
        }
       
        Assignable& operator=( const Assignable& other ) {
            cout << "Called assignment operator" << endl;
            this->vPublic = other.vPublic;
            this->vPrivate = other.vPrivate;
            return *this;
        }
       
        Assignable(const Assignable &other) {
            cout << "called copy constructor" << endl;
            this->vPublic = other.vPublic;
            this->vPrivate = other.vPrivate;
        }
       
        ~Assignable() {
            cout << "destructed" << endl;
        }
};

Assignable giveMeNewClassOptimized(int vPublic, int vPrivate) {
    Assignable nClass(vPublic);
    nClass.setPrivate(vPrivate);
    
    return nClass;
}

Assignable giveMeNewClassNoopt(int vPublic, int vPrivate) {
    Assignable *nClass = new Assignable(vPublic);
    nClass->setPrivate(vPrivate);
    
    return *nClass;
}
 
void printAssignable(Assignable a) {
    a.print();
}
 
int main()
{
    cout << "Hello World" << endl;
   
    int i = 2;
    if(i == 0) {
        cout << "Copy constructor call demo: when an instance of a class is passed "
                "as value to a function" << endl;
        Assignable a1(5);
        Assignable a2(10);
        a1.setPrivate(5);
        a2.setPrivate(10);
        
        printAssignable(a1);
    } else if(i == 1) {
        cout << "Copy constructor call demo: when a new instance of a class is "
                "created from an existing object" << endl;
        Assignable a1(5);
        a1.setPrivate(5);
        Assignable a2(a1);
        a2.print();
        
        cout << endl << "Another flavor:" << endl;
        Assignable a3 = a1;
        a3.print();
    } else if(i == 2) {
        cout << "Copy constructor call demo: when an instance of a class is "
                "returned by value " << endl;
        Assignable a1 = giveMeNewClassNoopt(55, 55);
        a1.print();
        
        cout << endl << "Another flavor:" << endl;
        Assignable a2 = giveMeNewClassOptimized(55, 55);
        a2.print();
        cout << "Don't be surprised if copy constructor is not called here. "
                "Compilers are known to optimize away this copy" << endl;
    } else if(i == 3) {
        Assignable a1(5);
        Assignable a2(10);
        a1.setPrivate(5);
        a2.setPrivate(10);
        
        a2 = a1;
        a2.print();
    }
   
   return 0;
}

final.cpp

#include <iostream>
 
using namespace std;
 
class Assignable {
    private:
        int vPrivate = 0;
    public:
        int vPublic = 0;
       
        Assignable() {
            vPrivate = 0;
            vPublic = 0;
            cout << "Constructed()" << endl;
        }
       
        explicit Assignable(int _public) : vPublic(_public) {
            cout << "Constructed(int)" << endl;
        }
       
        void setPrivate(int _private) {
            vPrivate = _private;
        }
       
        void print() const {
            cout << vPublic << " " << vPrivate << endl;
        }
       
        Assignable& operator=( const Assignable& other ) {
            cout << "Called assignment operator" << endl;
            this->vPublic = other.vPublic;
            this->vPrivate = other.vPrivate;
            return *this;
        }
       
        Assignable(const Assignable &other) {
            cout << "called copy constructor" << endl;
            this->vPublic = other.vPublic;
            this->vPrivate = other.vPrivate;
        }
       
        ~Assignable() {
            cout << "destructed" << endl;
        }
};

Assignable giveMeNewClassOptimized(int vPublic, int vPrivate) {
    Assignable nClass(vPublic);
    nClass.setPrivate(vPrivate);
    
    return nClass;
}

Assignable giveMeNewClassNoopt(int vPublic, int vPrivate) {
    Assignable *nClass = new Assignable(vPublic);
    nClass->setPrivate(vPrivate);
    
    return *nClass;
}
 
void printAssignable(Assignable a) {
    a.print();
}
 
int main()
{
    cout << "Hello World" << endl;
   
    int i = 2;
    if(i == 0) {
        cout << "Copy constructor call demo: when an instance of a class is passed "
                "as value to a function" << endl;
        Assignable a1(5);
        Assignable a2(10);
        a1.setPrivate(5);
        a2.setPrivate(10);
        
        printAssignable(a1);
    } else if(i == 1) {
        cout << "Copy constructor call demo: when a new instance of a class is "
                "created from an existing object" << endl;
        Assignable a1(5);
        a1.setPrivate(5);
        Assignable a2(a1);
        a2.print();
        
        cout << endl << "Another flavor:" << endl;
        Assignable a3 = a1;
        a3.print();
    } else if(i == 2) {
        cout << "Copy constructor call demo: when an instance of a class is "
                "returned by value " << endl;
        Assignable a1 = giveMeNewClassNoopt(55, 55);
        a1.print();
        
        cout << endl << "Another flavor:" << endl;
        Assignable a2 = giveMeNewClassOptimized(55, 55);
        a2.print();
        cout << "Don't be surprised if copy constructor is not called here. "
                "Compilers are known to optimize away this copy" << endl;
    } else if(i == 3) {
        Assignable a1(5);
        Assignable a2(10);
        a1.setPrivate(5);
        a2.setPrivate(10);
        
        a2 = a1;
        a2.print();
    }
   
   return 0;
}