Remove unused code and migrate to CMake build system.

cpp/pointer/CMakeLists.txt

@@ -0,0 +1,6 @@
+cmake_minimum_required(VERSION 4.1)
+project(pointer)
+
+set(CMAKE_CXX_STANDARD 20)
+
+add_executable(pointer main.cpp)

cpp/pointer/main.cpp

@@ -0,0 +1,102 @@
+#include <iostream>
+#include <memory>
+#include <ostream>
+
+void changeInt(int n);
+
+void changeIntPointer(int *pN);
+
+void changeIntReference(int &n);
+
+void createInt(int *pN);
+
+void createInt(int **ppN);
+
+int main() {
+    int i = 5;
+    int *pI = nullptr;
+    pI = &i;
+    *pI = 10;
+    pI = new int;
+    pI = new int(); // CAUTION - memory leak created
+    pI = new int(10); // CAUTION - memory leak created
+    delete pI;
+    pI = nullptr;
+
+    int &rI = i; // reference
+
+    changeInt(i);
+    changeIntPointer(&i);
+    changeIntReference(i);
+
+    createInt(pI);
+    createInt(&pI);
+
+    // const
+    // const int ci = 5; // constant integer
+    // const int* cpi = new int(0); // pointer to a constant integer
+    // cpi = new int(10);
+    // *cpi = 10;
+    // int const * pci = new int(0); // pointer to a constant integer
+    // pci = new int(10);
+    // *pci = 10;
+    // int * const pic = new int(0); // constant pointer to an integer
+    // pic = new int(10);
+    // *pic = 10;
+    // const int * const cpic = new int(0); // constant pointer to a constant integer
+    // cpic = new int(10);
+    // *cpic = 10;
+    // int const * const pcic = new int(0); // constant pointer to a constant integer
+    // pcic = new int(10);
+    // *pcic = 10;
+    // const int const * cpci = new int(0);
+    // const int const * const cpcic = new int(0);
+
+    std::unique_ptr<int> upi = std::make_unique<int>(10);
+    // std::unique_ptr<int> upi2 = upi; // don't work
+    std::unique_ptr<int> upi3 = std::make_unique<int>(*upi);
+
+    std::shared_ptr<int> spi = std::make_shared<int>(10);
+    std::shared_ptr<int> spi2 = spi;
+    spi.reset();
+
+    std::weak_ptr<int> wpi = spi2;
+    if (wpi.expired()) {
+        std::cout << "expired" << std::endl;
+    } else {
+        std::cout << "not expired" << std::endl;
+        std::shared_ptr<int> spi3 = wpi.lock();
+    }
+
+    spi2.reset();
+
+    if (wpi.expired()) {
+        std::cout << "expired" << std::endl;
+    } else {
+        std::cout << "not expired" << std::endl;
+    }
+
+    return 0;
+}
+
+void changeInt(int n) {
+    n *= 2;
+}
+
+void changeIntPointer(int *pN) {
+    if (pN == nullptr) return;
+    *pN *= 2;
+}
+
+void changeIntReference(int &n) {
+    n *= 2;
+}
+
+void createInt(int *pN) {
+    pN = new int(10);
+}
+
+void createInt(int **ppN) {
+    if (ppN == nullptr) return;
+    *ppN = new int(10);
+}