prepare for c++17

code/3/3.4.cpp

@@ -0,0 +1,31 @@
+//
+// 3.4.cpp
+// c++1x tutorial
+//
+// created by changkun at shiyanlou.com
+//
+// 移动语义
+
+#include <iostream>
+class A {
+public:
+    int *pointer;
+    A():pointer(new int(1)) { std::cout << "构造" << pointer << std::endl; }
+    A(A& a):pointer(new int(*a.pointer)) { std::cout << "拷贝" << pointer << std::endl; }    // 无意义的对象拷贝
+    A(A&& a):pointer(a.pointer) { a.pointer = nullptr;std::cout << "移动" << pointer << std::endl; }
+    ~A(){ std::cout << "析构" << pointer << std::endl; delete pointer; }
+};
+// 防止编译器优化
+A return_rvalue(bool test) {
+    A a,b;
+    if(test) return a;
+    else return b;
+}
+int main() {
+    A obj = return_rvalue(false);
+    std::cout << "obj:" << std::endl;
+    std::cout << obj.pointer << std::endl;
+    std::cout << *obj.pointer << std::endl;
+    
+    return 0;
+}