CH 1-4 : INTRODUCTION ACKNOWLEDGEMENT: THE SLIDES ARE PREPARED FROM SLIDES PROVIDED WITH DATA STRUCTURES AND ALGORITHMS IN C++, GOODRICH, TAMASSIA AND MOUNT (WILEY 2004) AND SLIDES FROM NANCY M. AMATO AND JORY DENNY 1

SYLLABUS  2

OBJECT ORIENTED DESIGN (CH 2)  Object Oriented Design and Principles  Abstract Data Types  Encapsulation  Inheritance  Polymorphism  Exceptions 3

OBJECT ORIENTED DESIGN AND PRINCIPLES (CH 2.1)  Design Goals:  Robustness : Capability to handle any type of inputs  Adaptability : Can be used in various environments with minimal or no changes  Reusability : Same code can be used as a component in various applications over time  Design Principles:  Abstraction: Abstract the complicated details in form of fundamental parts and operations  Encapsulation: Coupling data with methods.  Modularity: Component based design  Inheritance: Hierarchical and “is-a type-of” relationship  Polymorphism: Ability to take different form 4

ABSTRACT DATA TYPE (ADT)  An abstract data type (ADT) is an abstraction of a data structure  An ADT specifies:  Data stored  Operations on the data  Error conditions associated with operations  Mathematical model only with no details about the implementation :  ADT specifies what each operation does not how it does it.  Example: ADT modeling a simple stock trading system  The data stored are buy/sell orders  The operations supported are  order buy(stock, shares, price)  order sell(stock, shares, price)  void cancel(order)  Error conditions:  Buy/sell a nonexistent stock  Cancel a nonexistent order 5

ENCAPSULATION  Bundling of data and associated methods as a type.  Hiding the details and direct access to the underlying data.  Class: Construct or the definition of encapsulated data and associated methods. User-defined types.  class Person { private: string name; public: string GetName() { return name; } void SetName( string _n) { name = _n; } }  Object: Instance of an object  Person A; // A is an object of class Person or in other words type of A is Person 6

INHERITANCE  Hierarchical organization of classes.  Base class: The class from which another class is inherited.  Derived class: The class that inherits  Abstract classes: Base class with one or more virtual member functions  Virtual member functions are abstract functions with no details. 7 Shape CircleTriangleSquare

POLYMORPHISM  Different types of a variable  Subtyping : Type of the variable is determined at runtime based on the instance.  Eg: Shape* newShape = new Circle(); newShape->draw(); //Will call draw() function of Circle class and not of the Shape class.  Parametric: Generics (templates) where code is written without any specific type.  Eg: template T sum ( T a, T b) {} // Can be used as sum (3,4) and sum (4.5, 7.8) 8

EXCEPTIONS (CH 2.4)  Attempting the execution of an operation of ADT may sometimes cause an error condition, called an exception  Exceptions are said to be “thrown” by an operation that cannot be executed  Example: removing an element from an empty container 9

ARRAYS AND LINKED LISTS (CH 3)  Arrays (Ch 3.1)  Singly Linked List (Ch 3.2)  Doubly Linked (Ch 3.3) 10

ARRAYS  Data structure containing a collection of same type  Contiguous allocation in memory  Limitation: The length or capacity of the array is fixed.  Easy Random Access through index of the element (position of the element with respect to the first element in the array. Eg. A[3] indicates fourth element if the first element is stored in index 0.  Insertions and deletion at arbitrary location would include rearrangement of the elements following the location. Eg. Removing an element at index 6 would involve moving elements at indices 7,8,9 to 6,7,8. 11

SINGLY LINKED LIST  A singly linked list is a concrete data structure consisting of a sequence of nodes  Each node stores  element  link to the next node  No contiguous allocation of memory  Accessing an element at an arbitrary location includes traversing the list from the first element. next elem node ABCD  12

DOUBLY LINKED LIST  A doubly linked list provides a natural implementation of the Node List ADT  Nodes implement Position and store:  element  link to the previous node  link to the next node  Special trailer and header nodes  No contiguous allocation of memory  Access at arbitrary position requires traversal of the list  Easy insertion and deletion of element  If the pointer to the element is known prevnext elem trailer header nodes/positions elements node 13