book: translation of ch05

Update #12

code/5/5.1.cpp

@@ -1,66 +0,0 @@
-#include <iostream>
-#include <memory>
-
-void foo(std::shared_ptr<int> i)
-{
-    (*i)++;
-}
-
-
-//struct Base {
-//    Base() { std::cout << "  Base::Base()\n"; }
-//    ~Base() { std::cout << "  Base::~Base()\n"; }
-//};
-//
-//struct Subclass: public Base {
-//    Subclass() { std::cout << "  Subclass::Subclass()\n"; }
-//    ~Subclass() { std::cout << "  Subclass::~Subclass()\n"; }
-//};
-//
-//void thr(std::shared_ptr<Base> p)
-//{
-//    std::this_thread::sleep_for(std::chrono::seconds(1));
-//    std::shared_ptr<Base> lp = p; // 即使引用计数增加也是线程安全的
-//    {
-//        static std::mutex io_mutex;
-//        std::lock_guard<std::mutex> lk(io_mutex);
-//        std::cout << "local pointer in a thread:\n"
-//        << "  lp.get() = " << lp.get()
-//        << ", lp.use_count() = " << lp.use_count() << '\n';
-//    }
-//}
-
-int main()
-{
-    // auto pointer = new int(10); // 非法, 不允许直接赋值
-    // 构造了一个 std::shared_ptr
-    auto pointer = std::make_shared<int>(10);
-    auto pointer2 = pointer;    // 引用计数+1
-    auto pointer3 = pointer;    // 引用计数+1
-    
-    
-    foo(pointer);
-    std::cout << *pointer << std::endl; // 11
-    int *p = pointer.get();             // 这样不会增加引用计数
-    
-    std::cout << "pointer.use_count() = " << pointer.use_count() << std::endl;
-    std::cout << "pointer2.use_count() = " << pointer2.use_count() << std::endl;
-    std::cout << "pointer3.use_count() = " << pointer3.use_count() << std::endl;
-
-    pointer2.reset();
-    std::cout << "reset pointer2:" << std::endl;
-    std::cout << "pointer.use_count() = " << pointer.use_count() << std::endl;
-    std::cout << "pointer2.use_count() = " << pointer2.use_count() << std::endl;
-    std::cout << "pointer3.use_count() = " << pointer3.use_count() << std::endl;
-    
-    pointer3.reset();
-    std::cout << "reset pointer3:" << std::endl;
-    std::cout << "pointer.use_count() = " << pointer.use_count() << std::endl;
-    std::cout << "pointer2.use_count() = " << pointer2.use_count() << std::endl;
-    std::cout << "pointer3.use_count() = " << pointer3.use_count() << std::endl;
-    // std::cout << *pointer << std::endl; // 引用计数为0时, 非法访问
-    
-    
-    // 离开作用域前，pointer 会被析构，引用计数减为0, 从而释放内存
-    return 0;
-}

code/5/5.1.shared.ptr.a.cpp

@@ -0,0 +1,52 @@
+//
+// 5.1.shared.ptr.cpp
+// chapter 05 start pointers and memory management
+// modern c++ tutorial
+//
+// created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
+//
+
+#include <iostream>
+#include <memory>
+
+void foo(std::shared_ptr<int> i)
+{
+    (*i)++;
+}
+
+int main()
+{
+    // auto pointer = new int(10); // illegal, no direct assignment
+    // std::shared_ptr construction
+    auto pointer = std::make_shared<int>(10);
+    auto pointer2 = pointer;    // reference count + 1
+    auto pointer3 = pointer;    // reference count + 1
+    
+    
+    foo(pointer);
+    std::cout << *pointer << std::endl; // 11
+    int *p = pointer.get();             // does not increase reference count
+    
+    std::cout << "pointer.use_count() = " << pointer.use_count() << std::endl;
+    std::cout << "pointer2.use_count() = " << pointer2.use_count() << std::endl;
+    std::cout << "pointer3.use_count() = " << pointer3.use_count() << std::endl;
+
+    pointer2.reset();
+    std::cout << "reset pointer2:" << std::endl;
+    std::cout << "pointer.use_count() = " << pointer.use_count() << std::endl;
+    std::cout << "pointer2.use_count() = " << pointer2.use_count() << std::endl;
+    std::cout << "pointer3.use_count() = " << pointer3.use_count() << std::endl;
+    
+    pointer3.reset();
+    std::cout << "reset pointer3:" << std::endl;
+    std::cout << "pointer.use_count() = " << pointer.use_count() << std::endl;
+    std::cout << "pointer2.use_count() = " << pointer2.use_count() << std::endl;
+    std::cout << "pointer3.use_count() = " << pointer3.use_count() << std::endl;
+    // std::cout << *pointer << std::endl; // reference count equals 0, illegal access
+
+
+    // Before leaving the scope, the pointer is destructed and
+    // the reference count is reduced to 0
+    return 0;
+}

code/5/5.2.unique.ptr.cpp

@@ -1,3 +1,12 @@
+//
+// 5.2.unique.ptr.cpp
+// chapter 05 start pointers and memory management
+// modern c++ tutorial
+//
+// created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
+//
+
 #include <iostream>
 #include <memory>
 
@@ -14,28 +23,28 @@ void f(const Foo &) {
 int main() {
     std::unique_ptr<Foo> p1(std::make_unique<Foo>());
     
-    // p1 不空, 输出
+    // p1 is not empty, prints
     if (p1) p1->foo();
     {
         std::unique_ptr<Foo> p2(std::move(p1));
         
-        // p2 不空, 输出
+        // p2 is not empty, prints
         f(*p2);
         
-        // p2 不空, 输出
+        // p2 is not empty, prints
         if(p2) p2->foo();
         
-        // p1 为空, 无输出
+        // p1 is empty, no prints
         if(p1) p1->foo();
         
         p1 = std::move(p2);
         
-        // p2 为空, 无输出
+        // p2 is empty, no prints
         if(p2) p2->foo();
-        std::cout << "p2 被销毁" << std::endl;
+        std::cout << "p2 was destroied" << std::endl;
     }
-    // p1 不空, 输出
+    // p1 is not empty, prints
     if (p1) p1->foo();
     
-    // Foo 的实例会在离开作用域时被销毁
+    // Foo instance will be destroied when leaving the scope
 }

code/5/5.3.weak.ptr.cpp

@@ -1,3 +1,13 @@
+//
+// 5.3.weak.ptr.cpp
+// chapter 05 start pointers and memory management
+// modern c++ tutorial
+//
+// created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
+//
+
+
 #include <iostream>
 #include <memory>
 
@@ -8,14 +18,14 @@ class A {
 public:
     std::shared_ptr<B> pointer;
     ~A() {
-        std::cout << "A 被销毁" << std::endl;
+        std::cout << "A was destroied" << std::endl;
     }
 };
 class B {
 public:
     std::shared_ptr<A> pointer;
     ~B() {
-        std::cout << "B 被销毁" << std::endl;
+        std::cout << "B was destroied" << std::endl;
     }
 };
 int main() {

code/5/Makefile

@@ -0,0 +1,14 @@
+#
+# modern cpp tutorial
+#
+# created by changkun at changkun.de
+# https://github.com/changkun/modern-cpp-tutorial
+#
+
+all: $(patsubst %.cpp, %.out, $(wildcard *.cpp))
+
+%.out: %.cpp Makefile
+	clang++ $< -o $@ -std=c++2a -pedantic
+
+clean:
+	rm *.out