demo explicit need of calling copy ctorHEADmaster

2 files changed, 117 insertions, 0 deletions

diff --git a/inheritance_ctor_calls.cpp b/inheritance_ctor_calls.cpp
new file mode 100644
index 0000000..6d692a8
--- /dev/null
+++ b/inheritance_ctor_calls.cpp
@@ -0,0 +1,77 @@
+/* g++ -Wall -std=gnu++98 -pedantic -MD -O0 -g inheritance_ctor_calls.cpp -o inheritance_ctor_calls
+ *
+ * Note: line 64 is very IMPORTANT!
+ * output:
+ *
+ * node1 default ctor called
+ * node2 default ctor called with y
+ * node1 default ctor called
+ * node2 copy ctor called
+ *
+ */
+
+#include <iostream>
+
+class Node1
+{
+  public:
+    Node1() : x_(0) {
+        std::cout << "node1 default ctor called\n";
+    };
+    Node1(int x) : x_(x) {
+        std::cout << "node1 default ctor called with x\n";
+    };
+
+    virtual void foo() {
+        std::cout << "node1 foo called\n";
+    }
+
+    int x_;
+};
+
+class Node2 : public Node1
+{
+  public:
+    Node2() : y_(0) {
+        std::cout << "node2 default ctor called\n";
+    };
+    Node2(int y) : y_(y) {
+        std::cout << "node2 default ctor called with y\n";
+    };
+
+    Node2(const Node2 &n) : y_(0) {
+        std::cout << "node2 copy ctor called\n";
+    }
+
+    virtual void foo() {
+        std::cout << "node2 foo called\n";
+        /* invoke parent method */
+        Node1::foo();
+        /* do things unique to this class */
+        /* ... */
+    }
+
+    int y_;
+};
+
+class Collection : public Node2
+{
+  public:
+    /* only immediate base class may be initialized, Node1 is 2 level deep here hence error */
+    Collection() : /* Node1(2), error */ Node2(1), z(0) {
+    }
+    /* parent copy ctor needs to be invoked since derived class' copy ctor is overridden */
+    Collection(const Collection& c) : Node2(c), z(0) {
+        /* ... */
+    }
+
+    int z;
+};
+
+int main(int argc, char **argv)
+{
+    Collection c;
+    Collection d(c);
+
+    return 0;
+}
diff --git a/virtual_destructor.cpp b/virtual_destructor.cpp
new file mode 100644
index 0000000..75324c6
--- /dev/null
+++ b/virtual_destructor.cpp
@@ -0,0 +1,40 @@
+/* outputs:
+ *
+ * derived destructor called
+ * base destructor called
+ */
+
+#include <iostream>
+
+/* will generate a class's default ctor, copy ctor, copy assignment operator,
+ * by default data member and dtor are private, default ctor, copy ctor and
+ * assignment operator are public
+ */
+class Base
+{
+  public:
+    virtual ~Base();
+};
+Base::~Base() {
+    std::cout << "base destructor called\n";
+}
+
+class Derived : public Base
+{
+  public:
+    ~Derived();
+};
+Derived::~Derived() {
+    std::cout << "derived destructor called\n";
+}
+
+int main(int argc, char **argv)
+{
+    /* when d goes out of scope, it will call its destructor will call base
+     * class destructor
+     */
+    Derived d;
+    Base b = d; /* conversion of d into Base takes place on rhs, d is sliced down */
+
+    return 0;
+}