#include <iostream>

#include <memory>

class X {

public:

X() {

instance_count++;

instance_id = instance_count;

printf("[ %2d ] X's Constructor\n", instance_id);

}

~X() {

printf("[ %2d ] X's Destructor\n", instance_id);

}

void SayHi() {

printf("[ %2d ] Hi from X\n", instance_id);

}

private:

static int instance_count;

int instance_id;

};

int X::instance_count = 0;

void print_line() {

std::cout << "----------------------------------------------------------\n"; return;

}

void test_with_raw_ptr() {

print_line();

X *x = new X{};

x->SayHi();

print_line();

return;

}

// Example on how to return a unique_ptr;

// Here, Move semantics come into play.

// Ref: https://stackoverflow.com/questions/9827183/why-am-i-allowed-to-copy-unique-ptr

auto getXsUniquePtr() {

auto x = std::make_unique<X>();

// The following line is equivalent to return std::move(x)

return x;

}

void test_with_uniq_ptr() {

print_line();

auto x = std::make_unique<X>();

x->SayHi();

print_line();

// Unique Ptr cannot be copied.

// auto y = x;

// Reason:

// unique_ptr(const unique_ptr&) = delete;

// unique_ptr& operator=(const unique_ptr&) = delete;

// Example on how to return a unique_ptr;

// Here, Move semantics come into play.

// Ref: https://stackoverflow.com/questions/9827183/why-am-i-allowed-to-copy-unique-ptr

auto z = getXsUniquePtr();

x->SayHi();

print_line();

return;

}

int main() {

test_with_raw_ptr();

test_with_uniq_ptr();

return 0;

}