refactor: restructure project to build a library for each book chapter

chapters/CMakeLists.txt

@@ -0,0 +1 @@
+add_subdirectory(chapter_02)

chapters/chapter_02/CMakeLists.txt

@@ -0,0 +1,4 @@
+add_library(chapter_02 src/initlist.cpp src/null.cpp src/constexp.cpp
+                       src/ifswitch.cpp)
+
+target_include_directories(chapter_02 PUBLIC include)

chapters/chapter_02/include/constexp.h

@@ -0,0 +1,5 @@
+#pragma once
+
+namespace constexp {
+void test();
+};

chapters/chapter_02/include/ifswitch.h

@@ -0,0 +1,7 @@
+#pragma once
+
+namespace ifswitch {
+
+void test();
+
+};

chapters/chapter_02/include/initlist.h

@@ -0,0 +1,5 @@
+#pragma once
+
+namespace initlist {
+void test();
+};

chapters/chapter_02/include/null.h

@@ -0,0 +1,5 @@
+#pragma once
+
+namespace null {
+void test();
+};

chapters/chapter_02/src/constexp.cpp

@@ -0,0 +1,27 @@
+#include "constexp.h"
+#include <iostream>
+
+constexpr unsigned int fibonacci(const unsigned int n) {
+  if (n == 1 || n == 2) {
+    return 1;
+  }
+
+  return fibonacci(n - 2) + fibonacci(n - 1);
+}
+
+void constexp::test() {
+  std::cout << "Fibonacci(10): ";
+  for (const unsigned int n : {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
+    std::cout << fibonacci(n) << " ";
+  }
+  std::cout << std::endl;
+
+  int arr_1[fibonacci(10)];
+  std::cout << "Array is " << sizeof(arr_1) / sizeof(int) << " items long"
+            << std::endl;
+
+  constexpr unsigned int arr_2_len = 10;
+  int arr_2[arr_2_len];
+  std::cout << "Array is " << sizeof(arr_2) / sizeof(int) << " items long"
+            << std::endl;
+}

chapters/chapter_02/src/ifswitch.cpp

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+#include <algorithm>
+#include <cstdint>
+#include <iostream>
+#include <vector>
+
+#include "ifswitch.h"
+
+void ifswitch::test() {
+  std::vector<uint32_t> vec = {1, 2, 3, 4};
+
+  if (auto it = std::find(vec.begin(), vec.end(), 23); it != vec.end()) {
+    std::cout << "Found element 23 in vector" << std::endl;
+  } else {
+    std::cout << "No element 23 in vector" << std::endl;
+  }
+
+  switch (auto it = vec.rbegin(); *it) {
+  case 4:
+    std::cout << "Found 4 at the back" << std::endl;
+    break;
+  default:
+    std::cout << "No 4 at the back" << std::endl;
+    break;
+  }
+}

chapters/chapter_02/src/initlist.cpp

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+#include "initlist.h"
+#include <initializer_list>
+#include <iostream>
+#include <vector>
+
+class InitList {
+public:
+  std::vector<unsigned int> _list;
+
+  InitList(std::initializer_list<unsigned int> list) : _list(list) {}
+};
+
+void initlist::test() {
+
+  InitList initList{1, 2, 3, 4, 5};
+
+  std::cout << "InitList: ";
+  for (const auto &item : initList._list) {
+    std::cout << item << " ";
+  }
+  std::cout << std::endl;
+}

chapters/chapter_02/src/null.cpp

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+#include <iostream>
+#include <type_traits>
+
+#include "null.h"
+
+void call_test(char *) { std::cout << "call_test(char *) called" << std::endl; }
+
+void call_test(int) { std::cout << "call_test(int) called" << std::endl; }
+
+void null::test() {
+  if (std::is_same<decltype(NULL), decltype(0)>::value) {
+    std::cout << "NULL == 0" << std::endl;
+  }
+
+  if (std::is_same<decltype(NULL), decltype((void *)0)>::value) {
+    std::cout << "NULL == (void *)0" << std::endl;
+  }
+
+  if (std::is_same<decltype(NULL), decltype(__null)>::value) {
+    std::cout << "NULL == __null" << std::endl;
+  }
+
+  if (std::is_same<decltype(NULL), std::nullptr_t>::value) {
+    std::cout << "NULL == nullptr" << std::endl;
+  }
+
+  call_test(0);
+  call_test(nullptr);
+}