add smart pointers

add polymorphism
add destructor & copy constructor
add pointer-pointer

CPlusPlus/Pointers/functions.cpp

@@ -24,3 +24,17 @@ bool changeIntegerPerReference(int& n)
 	n *= 2;
 	return true;
 }
+
+bool createInteger(int* pN)
+{
+	pN = new int(0); // BAD BAD - creates a memory leak
+
+	return false;
+}
+
+bool createIntegerWithPointerPointer(int** ppN)
+{
+	*ppN = new int(0);
+
+	return true;
+}

CPlusPlus/Pointers/functions.h

@@ -3,4 +3,7 @@
 void changeInteger(int n);
 int changeIntegerPerReturn(int n);
 bool changeIntegerPerPointer(int* pN);
-bool changeIntegerPerReference(int& n);
+bool changeIntegerPerReference(int& n);
+
+bool createInteger(int* pN);
+bool createIntegerWithPointerPointer(int** ppN);

CPlusPlus/Pointers/main.cpp

@@ -1,4 +1,5 @@
 #include <iostream>
+#include <memory>
 
 #include "functions.h"
 
@@ -33,5 +34,45 @@ int main()
 	changeIntegerPerPointer(pNumber);
 	changeIntegerPerReference(number);
 
+	// smart pointer
+	// unique_ptr - only one owner exist for the object
+	// shared_ptr - can have multiple owners
+	// weak_ptr - is a loose connection to a shared pointer
+
+	unique_ptr<int> pNumber2 = make_unique<int>(10);
+	*pNumber2 = 100;
+	//unique_ptr<int> pNumber3 = pNumber2; // compiler error- you can't create a copy of an unique pointer
+	unique_ptr<int> pNumber4 = make_unique<int>(*pNumber2);
+
+	shared_ptr<int> pNumber5 = make_shared<int>(10);
+	shared_ptr<int> pNumber6 = pNumber5;
+
+	*pNumber6 = 100;
+
+	pNumber5.reset();
+
+	weak_ptr<int> pNumber7 = pNumber6;
+	//*pNumber7 = 1000; // compiler error, weak pointer has no direct access to a shared pointer, you have to create a new shared pointer
+
+	if (!pNumber7.expired())
+	{
+		shared_ptr<int> tmpSharedNumber = pNumber7.lock();
+		*tmpSharedNumber = 10000;
+	}
+
+	pNumber6.reset();
+	shared_ptr<int> tmpSharedNumber2 = pNumber7.lock();
+	if (tmpSharedNumber2 != nullptr) *tmpSharedNumber2 = 100000;
+
+	// pointer-pointer
+	createInteger(pNumber);
+	createIntegerWithPointerPointer(&pNumber);
+
+	if (pNumber != nullptr)
+	{
+		delete pNumber;
+		pNumber = nullptr;
+	}
+
 	return 0;
 }