1. ECE 264 Object-Oriented Software Development Instructor: Dr. Honggang Wang Fall 2012 Lecture 13: Exam 1 Preview

2. Lecture outline Announcements/Reminders  Lab 4 due next Monday, 10/08  Exam 1 on 10/10 (Wednesday 9:00 am- 9:50 am) General exam information Exam review: what we’ve covered so far (not an exhaustive list!)  Software design cycle  I/O Input: cin, output: cout Output formatting File I/O  Classes Defining classes Calling member functions Implementing classes in separate files 6/9/2016 ECE 264: Lecture 13 2

3. General exam information You may also use all paper-based materials such as lecture notes (printed), textbooks and other related materials. One 8.5” x 11” double-sided sheet of notes allowed All electronic devices (e.g., cellular phones, PDAs) and Computer are prohibited. ( reduced to 50 mins and the exam focuses on programming questions) Start as close to 9:00 as possible and last 50 minutes Exam will be held in Room S&E 212 3 questions, most of which have multiple parts  Short answer  Fill-in-the-blank  Understanding code (i.e., given some code, what’s output/what values do variables have?)  Writing short code sequences Sample exam1 on web site (“Exam 1 sample”) under “Schedule and Materials”“Exam 1 sample  Should at least give you idea of format  Note that topics were covered in a slightly different manner in previous years 6/9/2016 ECE 264: Lecture 13 3

4. Review: Basic I/O Input ( cin ) streams  Use cin to read values into variables E.g., cin >> x; Skips whitespace characters Input value must be compatible with type of x  Reading n characters: cin.get(buffer, n); Reading 1 character: cin.get(ch);  Reading an entire line (at most m characters): cin.getline(buffer, m)  May need cin.ignore(x) to skip characters Output ( cout ) streams  Can output multiple values in same statement cout << “x=“ << x << “, y=“ << y << endl; Namespaces  Introduced std namespace—includes cin, cout, etc.  Could include entire namespace: using namespace std;  Or, just include members being used: using std::cout; 6/9/2016 ECE 264: Lecture 13 4

5. 6/9/2016 ECE 264: Lecture 13 5 output 1,2 4.5 cm _ //Example1: Determine the output #include using std::cout; using std::cin; using std::endl; #include using std::string; int main() { int i, j; double x; string units = " cm"; cin >> i >> j; cin >> x; cout << "output \n"; cout << i << ',' << j << endl << x << units << endl; return 0; } //Input stream: 1 2 4.5

6. 6/9/2016 ECE 264: Lecture 13 6 //Example 2: Determine the output #include using std::cout; using std::cin; using std::endl; int main() { int i, j; double x, y; cin >> i >> j >> x >> y; cout << "First output " << endl; cout << i << ',' << j << ',' << x << ',' << y << endl; cin >> x >> y >> i >> j; cout << "Second output" << endl; cout << i << ',' << j << ',' << x << ',' << y << endl; return 0; } //Input stream is: 1 2 3.4 5 2 3 3.4 7 First output 1,2,3.4,5 Second output 3,2,2,3 _

7. Review: Formatted output, file I/O Output formatting  Change base with dec/oct/hex or setbase()  Change precision (# places after decimal point) with precision() or setprecision() Be sure to specify fixed format!  Force decimal point to be shown with showpoint  Specify field width with setw() or width() Gives max number of input characters for cin ( width() only) Gives number of output characters for cout  Change justification with left/right/internal showpos / showbase forces sign / base to be shown  Change fill characters with fill() or setfill() File I/O  Specify ifstream or ofstream  Must explicitly open or close file 6/9/2016 ECE 264: Lecture 13 7

8. Example: bases int main() { int number; cout << "Enter a decimal number: "; cin >> number; // input number // use hex stream manipulator to show hexadecimal number cout << number << " in hexadecimal is: " << hex << number << endl; // use oct stream manipulator to show octal number cout << dec << number << " in octal is: " << oct << number << endl; // use setbase stream manipulator to show decimal number cout << setbase( 10 ) << number << " in decimal is: " << number << endl; return 0; } // end main 6/9/2016 ECE 264: Lecture 13 8

9. Example: showpoint, setprecision #include using std::cin; using std::cout; using std::endl; using std::fixed; using std::showpoint; #include using std::setprecision; int main() { double i, j, x, y; cin >> i >> j >> x >> y; cout << fixed << showpoint; cout << "First output " << endl; cout << i << ',' << j << ',' << setprecision(3) << x << ',' << y << endl; return 0; } // Input stream is: 1 2 3.4 5 6/9/2016 ECE 264: Lecture 13 9 First output 1.000000,2.000000,3.400,5.000 _

10. Example: setfill, setw (cont.) int main() { int x = 10000; // display x cout << x << " printed as int right and left justified\n" << "and as hex with internal justification.\n" << "Using the default pad character (space):" << endl; // display x with base cout << showbase << setw( 10 ) << x << endl; // display x with left justification cout << left << setw( 10 ) << x << endl; // display x as hex with internal justification cout << internal << setw( 10 ) << hex << x << endl << endl; 6/9/2016 ECE 264: Lecture 13 10

11. Example: setfill, setw (cont.) // display x using padded characters (right justification) cout << right; cout.fill( '*' ); cout << setw( 10 ) << dec << x << endl; // display x using padded characters (left justification) cout << left << setw( 10 ) << setfill( '%' ) << x << endl; // display x using padded characters (internal justification) cout << internal << setw( 10 ) << setfill( '^' ) << hex << x << endl; return 0; } // end main 6/9/2016 ECE 264: Lecture 13 11

12. Example: setfill, setw (output) 6/9/2016 ECE 264: Lecture 13 12

13. Review: Classes Classes allow programmer to define their own types  Objects: instances of a class Each class typically contains  Data members: attributes for each object Each object has own copy of data members  Member functions: Tasks specific to class Often includes “set” & “get” (mutator/accessor) functions Changes made to member data in these functions remains persistent  Constructor(s): function called at object creation Default constructor takes no arguments  Should always define—set default value(s) for data member(s) Parameterized constructors initializes data members to specific values 6/9/2016 ECE 264: Lecture 13 13

14. Review: Classes (cont.) Data/functions can be public or private  Private members only accessible within member functions Access public members of class outside class definition using dot operator (. )  Example: GradeBook g1; g1.setCourseName(“ECE 264”); Good programming practice: Split class into declaration (.h ) and implementation (.cpp )  Declaration contains list of data, function prototypes  Implementation contains actual code for functions Must specify class name for each function: :: ([param list]) { } 6/9/2016 ECE 264: Lecture 13 14

15. Example: GradeBook.h #include using std::string; class GradeBook { public: GradeBook( ); GradeBook( string name ); void setCourseName(string name); string getCourseName(); void displayMessage(); private: string courseName; }; // end class GradeBook 6/9/2016 ECE 264: Lecture 13 15

16. Example: GradeBook.cpp // GradeBook.cpp #include “GradeBook.h” // Default constructor—initializes courseName // to empty string GradeBook::GradeBook( ) { setCourseName( "" ); } // end GradeBook constructor // Parameterized constructor GradeBook::GradeBook( string name ) { setCourseName( name ); } // end GradeBook constructor 6/9/2016 ECE 264: Lecture 13 16

17. Example: GradeBook.cpp (cont.) // function to set course name void GradeBook::setCourseName( string name ) { courseName = name; } // end function setCourseName // function to get the course name string GradeBook::getCourseName() { return courseName; } // end function getCourseName // display welcome message to user void GradeBook::displayMessage() { cout << "Welcome to the grade book for\n" << getCourseName() << endl; } // end function displayMessage 6/9/2016 ECE 264: Lecture 13 17

18. Good Luck! 6/9/2016 ECE 264: Lecture 13 18