CSS 342 Data Structures, Algorithms, and Discrete Mathematics I. Lecture 1. Yusuf Pisan

Transcription

1 CSS 342 Data Structures, Algorithms, and Discrete Mathematics I Lecture 1 Yusuf Pisan

2 Overview Syllabus Course Objectives "Hello World" Object-Oriented Programming CSS Linux Cluster Class Exercises Program Style Assignment-1 Quiz

3 CSS342 FAQ 1. I know Java, do I need to know C++ to take this course? 2. I missed the C++ boot camp, will this be a problem? 3. Can I use the 6th edition of the Carrano book? 4. Do I need a C++ intro book? 5. How much math is required for this class? 6. Should I take CSS332 as well? 7. Is this class a lot work? 8. Any advice on success?

4 Course Objectives: Why are you here? Design, implement, debug, and test Object-Oriented Programs (OOP) Learn C++ Course is not focused on teaching C++ but we will teach aspects of it In particular: objects, allocation/deallocation, pointers, operator overloading, constructors, templates, STL Understand key data structures utilized in programming stack, list, array, queue, binary search tree Introduce key algorithms and algorithmic techniques Recursion, Sorting, Searching Discrete math as the underpinnings of Computer Science Formally analyze complexity of algorithms: Big O space and time Induction, Propositional logic

5 In-Class Program: Hello World

6 Integrated Development Environments (IDEs) Course Page: Resources > C++ Compiled Resources

7 Getting to know your classmates Talk to at least 3 people get their communication information ( , text, facebook, phone, whatsapp

8 In-Class Program: Largest 1. Take 2 numbers from user and display largest 2. Keep taking numbers and display largest at each step 3. Keep taking numbers, display largest and display all numbers entered

9 Object Oriented Programming (OOP) Abstraction - hide unnecessary details Encapsulation - attributes and functions in class Modularity - problem divided into modules/classes Polymorphism - process objects differently based on their type Hierarchy - relationship between modules (is-a and part-of)

10 Why C++ System understanding (memory, OS, threads, etc) Memory allocation / deallocation Low level functionality Elegant Efficient Nice features Operator overloading Type safety The more languages you know, the easier they are to learn Object oriented

11 Design first Design modules before coding Interface specified: functions that are to be called Implementation is secondary Relationship between modules Include pre-conditions and post-conditions Modular design Re-use Loosely Coupled

12 Simple Complete Cohesive Descriptive Intuitive Minimal No Public Data Amenable to loosely couple Interface Design

13 Enforcing Abstraction in C++ Modules map to C++ classes Objects == instances myclassname myobject; Class is made of two files C++ Headers file contain interface and data definition (.h) Code files contain implementation (.cpp) In this class we will not use UML much as the.h file does an excellent job of describing the contract

14 In-Class Exercise Design an interface for a class representing a push/pop stack Write down your assumptions What type of data is being put into the stack What are the return values of the functions

15 class IntStack { public: bool Pop(); int Top(); bool Push(int number); int Size(); int Peek(); ; One possible Stack Interface

16 Programming Style / Guidelines Very important! Code is read much more than written 80-90% of the life of code is spent maintaining it compared to initially writing it* You are writing code for others not yourself You often inherit others code Consumer should not have to rely on comments to understand code Will be an important component in grade for class Good code follows prescribed style rules *

17 Programming Guidelines We ll use most ideas from Google C++ guidelines Resources > C++ Compiled Resources > Google Coding Style Code Snippets to help with style Resources > C++ Compiled Resources > Code Style Examples - Snippets

18 Programming Guidelines: Naming Definitions PascalCasing: RedTop, FirstInLine, BigScaryMonster lower camelcasing: blueballthingy, sock, theitem, lastinline PascalCasing for class names, namespaces, public functions camelcasing for parameters, assessors (getvalue, setvalue ), private functions CAPS_CAPS for const variables const int CARDS_IN_DECK = 52 Choose readable identifier names Readability over brevity Avoid underscores, hyphens, or other non-alphanumeric characters (except for const where underscore is acceptable)

19 Programming Guidelines: Spacing K & R Style - Google's preference void foo(char a, int b) { while (x < y) { x = 13; Allman Style void foo(char a, int b) { while (x < y) { x = 13;

20 Programming Guidelines: Comments Comment functions using // before the function Use in-line comments sparingly Use comments to describe something not obvious to someone reading the code Comments describing the use of the class should go in the interface definition (.h) Comments about the class operation and implementation should accompany the implementation (.cpp) // This function is based on the zipterian algorithm. int void Zip(string firstname) {

21 C++ Fundamentals: Input void TestIO() { int number; std::string str; std::cout << "Enter a number: "; std::cin >> number; std::cout << "Enter a string: "; std::cin >> str; std::cout << "Number: " << number << ", string: " << str << std::endl; // full line std::cin.ignore(); // ignores \n that cin >> str has lefted (if user pressed enter key) std::cout << "Enter your full name: "; std::getline ( std::cin, str); std::cout << "Hello, " << str << std::endl;

22 C++ Fundamentals: string #include <cassert> void TestString() { std::string strhello = "Hello"; std::string strworld = "World"; std::string strfull = strhello + " " + strworld; std::cout << strfull << std::endl; assert(strfull == "Hello World"); assert(strfull[0] == 'H'); assert(strfull[strfull.length() - 1] == 'd'); // Does not compile, + tries to act on C-strings // invalid operands of types 'const char [6]' and 'const char [6]' to... // std::string s1 = "Hello" + "World";

23 C++ Fundamentals: string void TestArray() { int nums[10]; nums[0] = 23; for (int i{0; i < 10; ++i) { std::cout << nums[i] << ", "; std::cout << std::endl; std::string str[10]; str[0] = "Hello"; for (int i{0; i < 10; ++i) { std::cout << str[i] << ", "; std::cout << std::endl;

24 In-Class Exercise Design an interface for a class representing a deck of playing cards Assume class Card and class Hand have already been defined

25 #include "card.h" #include "hand.h" const int CARDS_IN_DECK = 52; class Deck { public: Deck(); ~Deck(); Card DealSingleCard(); Hand DealHand(int number); void Shuffle(); void Cut(); int CountCardsRemaining(); void ReturnHand(Hand thehand); void ReturnCard(Card thecard); int CountValuesRemaining(int val); int CountSuitsRemaing(Suit suit); bool isempty(); bool iscomplete(); private: Card deck[cards_in_deck]; ;

26 Call by Value, Reference, const Reference struct Rectangle { int length; int width; ; // int Area(Rectangle rect) - value rect is copied // int Area(Rectangle &rect) - reference, we can change the value // int Area(const Rectangle &rect) - const reference, cannot change it { int temp; temp = rect.length; rect.length = 35; return (temp * rect.width); void TestRectangle() { int result; Rectangle r = {3, 3; result = Area(r); std::cout << "length = " << r.length << std::endl; std::cout << "width = " << r.width << std::endl; std::cout << "Area = " << result << std::endl;

27 In-Class Exercise Write a function which takes two strings and swaps them How do you want to pass the variables? by value by reference by const reference

28 // by value void swap(std::string a, std::string b) { std::string tmp = a; a = b; b = tmp; // by reference void swap(std::string& a, std::string& b) { std::string tmp = a; a = b; b = tmp; // by const reference void swap(const std::string& a, const std::string& b) { std::string tmp = a; a = b; b = tmp;

29 findmax - which version is appropriate int findmax(vector< int> &a) int findmax(vector< int> &a) int findmax(const vector<int> &a) { int max = a[0]; int i; for (i = 1; i < a.size(); i++) if (a[i] > max) max = a[i]; return max;

30 // // Created by Yusuf Pisan on 3/26/18. // // A simple Account that allows user to deposit and withdraw money #ifndef WEEK1_ACCOUNT_H #define WEEK1_ACCOUNT_H account.h #include <iostream> class Account { friend std::ostream &operator<<(std::ostream &out, const Account &acc); public: // constructor Account(); // destructor ~Account(); // get the current balance int GetBalance() const; // deposit money into account // return true if successful, false otherwise // deposit is always successful bool Deposit( int amount); // withdraw money from account // return true if successful, false if not enough money bool Withdraw( int amount); private: // current balance int balance; ; #endif //WEEK1_ACCOUNT_H

31 #include "account.h" account.cpp std::ostream &operator<<(std::ostream &out, const Account &acc) { out << "A<" << acc.balance << ">"; return out; Account::Account() { balance = 0; Account::~Account() { // nothing to do int Account::GetBalance() const { return balance; bool Account::Deposit(int amount) { balance += amount; return true; bool Account::Withdraw(int amount) { if (balance >= amount) { balance -= amount; return true; else { return false;

32 Assignment-1 Preview

33 Before next class Readings -- see syllabus Start Assignment 1 (worth less points than others) Login to CSS Linux Lab Join #slack - Ask questions - Answer questions