add collections

add pointers

CPlusPlus/Pointers/main.cpp

@@ -0,0 +1,37 @@
+#include <iostream>
+
+#include "functions.h"
+
+using namespace std;
+
+int main()
+{
+	// general
+	int* pNumber = nullptr; // pointer definition, always initialize a pointer (at least with nullptr)
+	pNumber = new int(0); // creates a new integer value on the heap
+
+	cout << "size of pointer: " << sizeof(pNumber) << endl;
+	cout << "size of pointer data: " << sizeof(*pNumber) << endl;
+
+	*pNumber = 789;
+
+	//pNumber = new int(0); // BAD BAD - memory leak, because we override an existin g pointer address with a new one without saving or deleting the old one
+
+	// here are 100s lines of code
+
+	if (pNumber != nullptr)
+	{
+		delete pNumber;
+		pNumber = nullptr;
+	}
+
+	// pointer as references outside local scope
+	int number = 10;
+	changeInteger(number);
+	number = changeIntegerPerReturn(number);
+	changeIntegerPerPointer(&number);
+	changeIntegerPerPointer(pNumber);
+	changeIntegerPerReference(number);
+
+	return 0;
+}