add pointer in classes

add interfaces

CPlusPlus/Collections/main.cpp

@@ -1,6 +1,7 @@
 #include <iostream>
 #include <vector>
 #include <list>
+#include <algorithm>
 
 using namespace std;
 
@@ -42,7 +43,38 @@ int main()
 	printArray(numbers4);
 	printArray(numbers4, size(numbers4));
 
-	// "dynamic" (...) arrays
+	// "dynamic" heap arrays
+	int count2 = 10;
+	int* pNumbers = new int[count2];
+	pNumbers[0] = 10;
+	int* pNumber = pNumbers; // pNumber points onto the first element
+	//pNumber++; // pNumber points onto the second element
+	//pNumber--;
+	//pNumber += 2;
+	cout << "\"dynamic\" heap arrays" << endl;
+	for (size_t i = 0; i < count2; i++) // CAUTION - size is not working with heap arrays, we have to remember the size of the array
+	{
+		cout << pNumber << ": " << *pNumber << endl;
+		pNumber++;
+	}
+	delete[] pNumbers; // CAUTION - heap arrays have to be deleted with delete[]
+	pNumbers = pNumber = nullptr;
+
+	// 2d arrays
+	int** p2dArray = new int* [10];
+	for (size_t i = 0; i < 10; i++)
+	{
+		p2dArray[i] = new int[10];
+	}
+
+	// for delete -> delete inner arrays first
+	for (size_t i = 0; i < 10; i++)
+	{
+		delete[] p2dArray[i];
+		p2dArray[i] = nullptr;
+	}
+	delete[] p2dArray; // then outer array
+	p2dArray = nullptr;
 
 	// stl collections
 	vector<int> numbers5;
@@ -60,6 +92,28 @@ int main()
 	numbersList.push_back(10);
 	numbersList.push_front(0);
 	//numbersList[0] = 100; // random access is not available for lists
+	list<int>::iterator it = numbersList.begin();
+	for (; it != numbersList.end(); it++)
+	{
+		cout << *it << " ";
+	}
+	cout << endl;
+
+	numbersList.insert(--it, 20);
+
+	for (it = numbersList.begin(); it != numbersList.end(); it++)
+	{
+		cout << *it << " ";
+	}
+	cout << endl;
+
+	for (int n : numbersList)
+	{ }
+
+	// https://cppreference.com/w/cpp/algorithm.html
+	for_each(numbersList.begin(), numbersList.end(), [](const int& n) {
+
+	});
 
 	return 0;
 }