Added: C++ projects

CPlusPlus/Collections/.idea/.gitignore

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+# Default ignored files
+/shelf/
+/workspace.xml
+# Editor-based HTTP Client requests
+/httpRequests/
+# Ignored default folder with query files
+/queries/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml

CPlusPlus/Collections/.idea/encodings.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="Encoding" addBOMForNewFiles="with BOM under Windows, with no BOM otherwise" />
+</project>

CPlusPlus/Collections/CMakeLists.txt

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+cmake_minimum_required(VERSION 4.3)
+project(Collections)
+
+set(CMAKE_CXX_STANDARD 20)
+
+add_executable(Collections main.cpp
+        helpers.h
+        helpers.cpp)

CPlusPlus/Collections/helpers.cpp

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+//
+// Created by David Hackbarth on 21.09.26.
+//
+
+#include "helpers.h"
+
+#include <iostream>
+#include <ranges>
+
+int calculateGridIndex(int row, int column)
+{
+    return row * COLUMNS + column;
+}
+
+void printArray(int numbers[])
+{
+    int length = sizeof(numbers) / sizeof(numbers[0]);
+    // int length2 = std::ranges::size(numbers);
+
+    for (int i = 0; i < length; ++i)
+    {
+        std::cout << "numbers[" << i << "]:" << numbers[i] << std::endl;
+    }
+}
+
+void printArray(int numbers[], size_t length)
+{
+    for (int i = 0; i < length; ++i)
+    {
+        std::cout << "numbers[" << i << "]:" << numbers[i] << std::endl;
+    }
+}

CPlusPlus/Collections/helpers.h

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+//
+// Created by David Hackbarth on 21.09.26.
+//
+
+#ifndef COLLECTIONS_HELPERS_H
+#define COLLECTIONS_HELPERS_H
+
+#include <iostream>
+
+#define ROWS 5
+#define COLUMNS 10
+
+int calculateGridIndex(int row, int column);
+void printArray(int numbers[]);
+void printArray(int numbers[], size_t length);
+
+template <typename T>
+void printVector(std::vector<T> numbers)
+{
+    for (int i = 0; i < numbers.size(); ++i)
+    {
+        std::cout << "numbers[" << i << "]:" << numbers[i] << std::endl;
+    }
+}
+
+#endif //COLLECTIONS_HELPERS_H

CPlusPlus/Collections/main.cpp

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+#include <iostream>
+#include <list>
+#include <vector>
+
+#include "helpers.h"
+
+using namespace std;
+
+// int main()
+int main(int argc, char* argv[])
+{
+    // C arrays
+    int numbers[10];
+
+    for (int i = 0; i < 10; ++i)
+    {
+        numbers[i] = 0;
+    }
+
+    int numbers2[] = {0, 1, 2, 3, 4};
+    int numbers3[10] = {0, 1, 2, 3, 4};
+
+    numbers[0] = 1;
+
+    cout << "numbers[5]: " << numbers[5] << endl;
+    cout << "numbers2[5]: " << numbers2[5] << endl;
+    cout << "numbers3[5]: " << numbers3[5] << endl;
+
+    // 2D array - 10 columns, 5 rows
+    int grid[ROWS * COLUMNS] = {};
+    grid[calculateGridIndex(0, 0)] = 1;
+
+    int grid2[ROWS][COLUMNS] = {};
+
+    // size of an array has to be constant always
+    const int COUNT = 10;
+    int numbers4[COUNT] = {};
+
+    // "dynamic" heap arrays
+    int count2 = 10;
+    int* pNumbers = new int[count2];
+    pNumbers[0] = 1;
+    int* pNumbers2 = pNumbers; // pointer looks onto first element
+    for (size_t i = 0; i < count2; i++) // size can't be used for heap arrays
+    {
+        cout << pNumbers2 << ": " << *pNumbers2 << endl;
+        pNumbers2++;
+    }
+    delete[] pNumbers; // CAUTION - heap arrays have to be deleted with delete[]
+    pNumbers = pNumbers2 = nullptr;
+
+    // 2d heap arrays
+    int** pGrid = new int*[ROWS];
+    for (size_t i = 0; i < ROWS; i++)
+    {
+        pGrid[i] = new int[COLUMNS];
+    }
+
+    for (size_t i = 0; i < ROWS; i++)
+    {
+        // delete inner arrays first
+        delete[] pGrid[i];
+        pGrid[i] = nullptr;
+    }
+    delete[] pGrid; // delete outer array
+    pGrid = nullptr;
+
+    int length = sizeof(numbers) / sizeof(numbers[0]);
+    int length2 = size(numbers);
+
+    printArray(numbers);
+    printArray(numbers, length);
+
+    // stl collections
+    std::vector<int> numbers5 = {0, 1, 2, 3, 4};
+    vector<int> numbers6;
+    vector<int> numbers7(100);
+
+    cout << "numbers5 size is " << numbers5.size() << " of " << numbers5.capacity() << endl;
+    cout << "numbers6 size is " << numbers6.size() << " of " << numbers6.capacity() << endl;
+    cout << "numbers7 size is " << numbers7.size() << " of " << numbers7.capacity() << endl;
+
+    numbers5.push_back(100);
+    numbers6.push_back(100);
+    numbers7.push_back(100);
+
+    cout << "numbers5 size is " << numbers5.size() << " of " << numbers5.capacity() << endl;
+    cout << "numbers6 size is " << numbers6.size() << " of " << numbers6.capacity() << endl;
+    cout << "numbers7 size is " << numbers7.size() << " of " << numbers7.capacity() << endl;
+
+    numbers5.pop_back();
+    numbers5.pop_back();
+    // numbers6.pop_back(); numbers6.pop_back(); // BE CAREFUL: also stl containers have no safety checks
+    numbers7.pop_back();
+    numbers7.pop_back();
+
+    cout << "numbers5 size is " << numbers5.size() << " of " << numbers5.capacity() << endl;
+    cout << "numbers6 size is " << numbers6.size() << " of " << numbers6.capacity() << endl;
+    cout << "numbers7 size is " << numbers7.size() << " of " << numbers7.capacity() << endl;
+
+    numbers6[0] = 200;
+    numbers6.reserve(1000);
+    numbers6.shrink_to_fit();
+
+    printArray(numbers6.data(), numbers6.size());
+
+    list<int> numbers8;
+    list<int> numbers9 = {0, 1, 2, 3, 4};
+    // numbers9[3] = 10; // random access is not available in list
+    list<int>::iterator it = numbers9.begin();
+    for (; it != numbers9.end(); ++it)
+    {
+        cout << *it << " ";
+    }
+    cout << endl;
+
+    numbers9.push_front(-1);
+    numbers9.push_back(5);
+
+    it = numbers9.begin(); // -1
+    it++; // 0
+    it++; // 1
+    it++; // 2
+    numbers9.insert(it, 15);
+
+    for (it = numbers9.begin(); it != numbers9.end(); ++it)
+    {
+        cout << *it << " ";
+    }
+    cout << endl;
+
+    for (int n : numbers9)
+    {
+
+    }
+
+    for_each(numbers9.begin(), numbers9.end(), [](int n) { cout << n << " "; });
+    cout << endl;
+
+    return 0;
+}