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virtual/set3/virtual_inline.cpp

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+/**
+ * @file virtual_inline.cpp
+ * @brief 通常类成员函数都会被编译器考虑是否进行内联。 
+ * 但通过基类指针或者引用调用的虚函数必定不能被内联。
+ * 当然，实体对象调用虚函数或者静态调用时可以被内联，虚析构函数的静态调用也一定会被内联展开。
+ * @author 光城
+ * @version v1
+ * @date 2019-07-24
+ */
+
+#include <iostream> 
+using namespace std; 
+class Base 
+{ 
+    public: 
+        virtual void who() 
+        { 
+            cout << "I am Base\n"; 
+        } 
+}; 
+class Derived: public Base 
+{ 
+    public: 
+        void who() 
+        {  
+            cout << "I am Derived\n"; 
+        } 
+}; 
+
+int main() 
+{ 
+    // note here virtual function who() is called through 
+    // object of the class (it will be resolved at compile 
+    // time) so it can be inlined. 
+    Base b; 
+    b.who(); 
+
+    // Here virtual function is called through pointer, 
+    // so it cannot be inlined 
+    Base *ptr = new Derived(); 
+    ptr->who(); 
+
+    return 0; 
+}