code. compile. run. debug. share.
Source Code
Language
#include <iostream>
#include <memory>
class Base {
public:
virtual void hello() {
std::cout << "hello" << std::endl;
}
};
class Derived : public Base {
public:
void hello() override {
std::cout << "derived hello" << std::endl;
}
};
// return make_unique
std::unique_ptr<Base> GetDerived()
{
std::cout << "GetDerived()" << std::endl;
return std::unique_ptr<Base>(std::make_unique<Derived>());
// The below line equals to the above.
//return std::make_unique<Derived>();
}
// return auto ptr instead of unique_ptr
std::unique_ptr<Base> GetDerived1()
{
std::cout << "GetDerived1() - Method 1" << std::endl;
auto a = std::make_unique<Derived>();
return a;
}
#if 0
// return by casting lvalue
std::unique_ptr<Base> GetDerived2()
{
std::cout << "GetDerived2() - Method 2" << std::endl;
std::unique_ptr<Derived> a = std::make_unique<Derived>();
return std::unique_ptr<Base>(a);
}
#endif
// return as move(lvalue)
std::unique_ptr<Base> GetDerived3()
{
std::cout << "GetDerived3()" << std::endl;
auto a = std::make_unique<Derived>();
return std::move(a);
}
// return auto ptr as lvalue
std::unique_ptr<Base> GetDerived4()
{
std::cout << "GetDerived4()" << std::endl;
auto a = std::make_unique<Base>();
return a;
}
// return auto ptr lvalue by casting
std::unique_ptr<Base> GetDerived5()
{
std::cout << "GetDerived5()" << std::endl;
auto a = std::make_unique<Base>();
return std::move(a);
}
int main()
{
std::unique_ptr<Base> gd = GetDerived();
std::unique_ptr<Base> gd1 = GetDerived1();
std::unique_ptr<Base> gd3 = GetDerived3();
std::unique_ptr<Base> gd4 = GetDerived4();
std::unique_ptr<Base> gd5 = GetDerived5();
return 1;
}
Compiling Program...
Standard Input:
Interactive Console
Text
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