hwr2023_a/CPlusPlus/intro/main.cpp

#include <iostream>
#include <Windows.h>
#include <memory>
#include <vector>
#include <list>
#include "functions.h"
#include "ClassA.h"
#include "ClassB.h"

int number = 0;

using namespace std;

void functionB() {}
void functionC();
void functionD(); // forward declaration

int main()
{
	//std::cout << "Hello World!" << std::endl;
	//cout << "Hallo" << endl;

	////functionA(); // compiler error - function not defined
	//functionB(); // no error
	////functionC(); // linker error - function declared, but not defined
	//functionD(); // no error
	////functionE(); // linker error - function is defined twice, because of two includes in two source files
	//functionF(); // no error

	//short s = 0;
	//unsigned short us = 0;
	//int i = 0;
	//long l = 0;

	//cout << "size of short: " << sizeof(s) << endl;
	//cout << "size of int: " << sizeof(i) << endl;
	//cout << "size of long: " << sizeof(l) << endl;
	//cout << "size of long long: " << sizeof(long long) << endl;
	//cout << "size of bool: " << sizeof(bool) << endl;

	//BYTE b;

	//cin >> number;
	//cout << "number: " << number << endl;

	//char c;
	//cin >> c;
	//cout << "c: " << c << endl;

	//string str;
	//cin >> str;
	//cout << "str: " << str << endl;

	//char sz[128];
	//cin >> sz;
	//cout << "sz: " << sz << endl;
	//cin >> sz;
	//cout << "sz: " << sz << endl;

	//int numbers[10] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
	//int* pNumber = new int(0);

	//cout << "local array print" << endl;
	//for (size_t i = 0; i < sizeof(numbers) / sizeof(int); i++)
	//{
	//	std::cout << numbers[i] << " ";
	//}
	//std::cout << std::endl;

	//cout << "function array print" << endl;
	//printArray(numbers, size(numbers));

	//int n = 1;
	//changeInt(n);
	//cout << "n (" << &n << "): " << n << endl;
	//changeIntPointer(&n);
	//cout << "n (" << &n << "): " << n << endl;

	//int* pN = nullptr;
	//int* pN2 = new int;
	//*pN2 = 1234;
	//delete pN2;
	//pN2 = nullptr;

	//if (pN2 != nullptr)
	//{
	//	*pN2 = 1234;
	//}

	//pN = new int;
	//*pN += 10;
	//pN = new int; // BAD - Memory Leak

	//changeIntReference(n);
	//cout << "n (" << &n << "): " << n << endl;

	//unique_ptr<int> un = make_unique<int>(0);
	//*un = 10;
	////unique_ptr<int> un2 = un; // not possible, because it is unique

	//shared_ptr<int> sn = make_shared<int>(0);
	//*sn = 10;
	//cout << "sn refs: " << sn.use_count() << endl;
	//shared_ptr<int> sn2 = sn;
	//cout << "sn refs: " << sn.use_count() << endl;
	//sn.reset();
	//cout << "sn refs: " << sn.use_count() << endl;
	//cout << "sn2 refs: " << sn2.use_count() << endl;

	//weak_ptr<int> wn = sn2;
	//cout << "sn2 refs: " << sn2.use_count() << endl;
	//if (!wn.expired()) 
	//{
	//	shared_ptr<int> ln = wn.lock();
	//	*ln *= 23;
	//	cout << "sn2 refs: " << sn2.use_count() << endl;
	//}

	//cout << "sn2 refs: " << sn2.use_count() << endl;

	//ClassA classA;
	//ClassA classA2 = classA;
	//ClassB classB;

	//int number = classA.GetNumber();
	//cout << number << endl;
	//classB.GetNumber();

	//IComparable* pComparable = nullptr;
	//pComparable = new ClassB();
	////ClassB* pClassB2 = (ClassB*)pComparable; // C-Cast, CAUTION: DANGER!!!
	//ClassB* pClassB2 = dynamic_cast<ClassB*>(pComparable); // C++ polymorph cast
	//float f = 1.0f;
	//int i = static_cast<int>(f); // explicit c++ cast between two static data types
	////int* pNonsense = reinterpret_cast<int*>(pComparable); // c++ cast like C-Cast
	//const char csz[13] = "Hello World";
	//char* sz = const_cast<char*>(csz);

	// What's the difference?
	//const int* cip;
	//int const* icp;
	//int* const ipc;
	//const int* const cipc;
	//int const* const icpc;
	//const int const* const cicpc;

	//IComparable* pComparable = nullptr;
	//IComparable* pComparable2 = new ClassA();
	//pComparable = new ClassB();
	//(*pComparable).Compare(pComparable2);
	//pComparable->Compare(pComparable2); // identical to line above, but simpler
	//delete pComparable;
	//pComparable = nullptr;
	////delete pComparable2;
	////pComparable2 = nullptr;
	//safeDelete(pComparable2);

	//vector<int> numbers = { 0, 10, 15, 4, 457 };
	//cout << "numbers size/capacity: " << numbers.size() << " / " << numbers.capacity() << endl;
	//numbers.push_back(999);
	//cout << "numbers size/capacity: " << numbers.size() << " / " << numbers.capacity() << endl;
	//numbers[3] = 65;

	//list<int> numbers2 = { 0, 10, 15, 4, 457 };
	//list<int>::iterator it = numbers2.begin();
	//for (; it != numbers2.end(); it++)
	//{
	//	//*it *= 2;
	//	cout << *it << " ";
	//}
	//cout << endl;
	//numbers2.insert(--it, 999);

	//for (it = numbers2.begin(); it != numbers2.end(); it++)
	//{
	//	//*it *= 2;
	//	cout << *it << " ";
	//}
	//cout << endl;

	const size_t count = 5;
	int numbers[count]; // const size -> stack array

	size_t count2 = 10;
	int* numbers2 = new int[count2]; // variable size -> heap array
	delete[] numbers2;
	numbers2 = nullptr;

	return 0;
}

void functionA() {}

void functionD() {}