diff --git a/08-InitializerList.cpp b/08-InitializerList.cpp
index 0157994..e6bea8a 100644
--- a/08-InitializerList.cpp
+++ b/08-InitializerList.cpp
@@ -20,6 +20,24 @@ void f(T (&c)[N]){
 	std::cout << std::endl;
 }
 
+//List Traversal.
+void g(std::initializer_list<int> l){
+	//Method 1
+	for(int i = 0; i < l.size(); ++i)
+		std::cout << l.begin()[i] << " ";
+	std::cout << std::endl;
+	
+	//Method 2
+	for(auto p = l.begin(); p != l.end(); ++p)
+		std::cout << *p << " ";
+	std::cout << std::endl;
+	
+	//Method 3
+	for(auto a: l)
+		std::cout << a << " ";
+	std::cout << std::endl;
+}
+
 int main(){
 	C c{1, 2, 3};
 	std::cout << c.data[0] << std::endl;
@@ -37,4 +55,6 @@ int main(){
 	};
 	
 	f(a);
+	
+	g({1, 2, 3, 4, 5});
 }
\ No newline at end of file
diff --git a/48-RuleOfFive.cpp b/48-RuleOfFive.cpp
new file mode 100644
index 0000000..ee0a444
--- /dev/null
+++ b/48-RuleOfFive.cpp
@@ -0,0 +1,58 @@
+//48-RuleOfFive
+
+#include <iostream>
+
+class A{
+public:
+	A(); //default constructor.
+	A(int); //user-defined constructor.
+	~A(); //destructor.
+	A(const A&); //copy constructor.
+	A(A&&); //move constructor.
+	A& operator=(const A&); //copy assignment.
+	A& operator=(A&&); //move assignment.
+	
+	int a;
+};
+
+A::A(): a{0}{
+	std::cout << "default constructor." << std::endl;
+}
+
+A::A(int x): a{x}{
+	std::cout << "user defined constructor." << std::endl;
+}
+
+A::~A(){
+	std::cout << "destructor." << std::endl;
+}
+
+A::A(const A& x): a{x.a}{
+	std::cout << "copy constructor." << std::endl;
+}
+
+A::A(A&& x): a{x.a}{
+	std::cout << "move constructor." << std::endl;
+}
+
+A& A::operator=(const A& x){
+	A t{x.a};
+	std::cout << "copy assignment." << std::endl;
+	return t;
+}
+
+A& A::operator=(A&& x){
+	A t{x.a};
+	std::cout << "move assignment." << std::endl;
+	return t;
+}
+
+int main(){
+	A a;
+	A b{1};	
+	A c{a};	
+	A d{};
+	
+	a = b;
+	d = std::move(a);
+}
\ No newline at end of file
diff --git a/49-ExplicitDestructor.cpp b/49-ExplicitDestructor.cpp
new file mode 100644
index 0000000..cdafef0
--- /dev/null
+++ b/49-ExplicitDestructor.cpp
@@ -0,0 +1,32 @@
+//49-ExplicitDestructor
+
+#include <iostream>
+
+class A{
+public:
+	A();
+	//~A(); //implicit destructor.
+	void destroy();
+private:
+	~A(); //explicit destructor. won't be invoked automatically 
+};
+
+A::A(){
+	std::cout << "constructor." << std::endl;
+}
+
+A::~A(){
+	std::cout << "destructor." << std::endl;
+}
+
+void A::destroy(){
+	this->~A();
+}
+
+int main(){
+	//A a; //error.
+	A* a = new A();
+	
+	//delete a; //error.
+	a->destroy();	
+}
\ No newline at end of file
diff --git a/MODERNCPP_REMINDER.txt b/MODERNCPP_REMINDER.txt
index 2964f40..ff2bf93 100644
--- a/MODERNCPP_REMINDER.txt
+++ b/MODERNCPP_REMINDER.txt
@@ -100,6 +100,7 @@
 * Postcondition: condition that must always be true just after execution of code.
 * Assertion: condition connected to point in program, that always should evaluate to true at that point in code execution.
 * PIMPL: pointer to implementation.
+* Rule of Five: if class has destructor that performs nontrivial task, such as free-store deallocation or lock release, class is likely to need full complement of functions: user-defined/copy/move constructors, copy/move assignments.
 
 
 [C++ ENTITIES]
@@ -379,12 +380,19 @@
 * declare constructor that can be called with single argument explicit.
 * const does not apply (transitively) to objects accessed through pointers or references.
 * nested class can refer to types and static members of its enclosing class, but has no notion of current object of enclosing class.
-
* Nifty Counter Idiom: 
-* Return Value Optimization: 
 * Dynamic Binding During Initialization Idiom: calling virtuals during initialization.
 * Don’t pass arrays as pointers, pass object representing range.
 * Prefer struct as parameter type rather than long argument list.
 * Prefer abstract classes as interfaces to class hierarchies.
+* Separate interface of class from its implementation.
+* Destructor will be implicitly invoked whenever X goes out of scope or is deleted.
+* Destruction can be prevented by declaring destructor =delete or private.
+* virtual destructor in base class makes it possible to delete appropriate derived class destructor.
+* default constructor disappears when you define constructor requiring arguments. copy constructor does not disappear.
+* references and consts must be initialized.
+
* Nifty Counter Idiom: 
+* Return Value Optimization: 
+
 
 
 [ISO CPP GUIDELINESS]
diff --git a/README.md b/README.md
index 6519aac..27d1f03 100644
--- a/README.md
+++ b/README.md
@@ -50,4 +50,6 @@
 - 44-StaticMember
 - 45-TemplateSpecialization
 - 46-SFINAE
-- 47-TemplateDerivedClass
\ No newline at end of file
+- 47-TemplateDerivedClass
+- 48-RuleOfFive
+- 49-ExplicitDestructor
\ No newline at end of file