1. ECE 264 Object-Oriented Software Development Instructor: Dr. Honggang Wang Spring 2013 Lecture 5: Continuing with output formatting

2. Lecture outline Announcements/reminders  Lab 2 (Wednesday session) due 02/08 (Friday)  Lab 2 (Monday session) due on 02/13 (Wednesday) Will submit to M:\ECE-264\ Review: output formatting  Changing precision  Forcing decimal point to be displayed Today  Continue with output formatting Changing field widths Changing justification within fields Changing fill characters  File I/O  Writing Code Together (WCT session) NEW!! 1/10/2016 ECE 264: Lecture 7 2

3. Review 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 1/10/2016 ECE 264: Lecture 7 3

4. Field Width ( width, setw ) Field width  (for ostream ) Number of character positions in which value is outputted Fill characters are inserted as padding Values wider than the field are not truncated  (for istream ) Maximum number of characters inputted For char array, maximum of one fewer characters than the width will be read (to accommodate null character) 1/10/2016 ECE 264: Lecture 7 4

5. Field Width ( width, setw ) (Cont.) Field width (Cont.)  Member function width of base class ios_base Sets the field width Returns the previous width  width function call with no arguments just returns the current setting  Parameterized stream manipulator setw Sets the field width  Field width settings are not sticky 1/10/2016 ECE 264: Lecture 7 5

6. Example 5: width // Fig. 15.10: Fig15_10.cpp: Demonstrating member function width. #include using std::cin; using std::cout; using std::endl; int main() { int widthValue = 4; char sentence[ 10 ]; cout << "Enter a sentence:" << endl; // set field width, then display characters based on that width do { cin.width( 5 ); // input only 5 characters from sentence cin >> sentence; cout.width( widthValue++ ); cout << sentence << endl; } while (sentence[0] != ‘.’); // end while return 0; } // end main 1/10/2016 ECE 264: Lecture 7 6

7. Example 5 output Enter a sentence: This is a test of the width member function. This is a test of the widt h memb er func tion. 1/10/2016 ECE 264: Lecture 7 7

8. Justification ( left, right and internal ) Justification in a field  Manipulator left fields are left-justified padding characters to the right  Manipulator right fields are right-justified padding characters to the left  Manipulator internal signs or bases on the left  showpos forces the plus sign to print  showbase forces the base to print (for octal/hex) magnitudes on the right padding characters in the middle 1/10/2016 ECE 264: Lecture 7 8

9. Example 6: right/left justification // Fig. 15.14: Fig15_14.cpp--Demonstrating left justification and right justification. #include using std::cout; using std::endl; using std::left; using std::right; #include using std::setw; int main() { int x = 12345; // display x right justified (default) cout << "Default is right justified:" << endl << setw( 10 ) << x; // use left manipulator to display x left justified cout << "\n\nUse std::left to left justify x:\n" << left << setw( 10 ) << x; // use right manipulator to display x right justified cout << "\n\nUse std::right to right justify x:\n" << right << setw( 10 ) << x << endl; return 0; } // end main 1/10/2016 ECE 264: Lecture 7 9

10. Example 7: internal justification // Fig. 15.15: Fig15_15.cpp // Printing an integer with internal spacing and plus sign. #include using std::cout; using std::endl; using std::internal; using std::showpos; #include using std::setw; int main() { // display value with internal spacing and plus sign cout << internal << showpos << setw( 10 ) << 123 << endl; return 0; } // end main 1/10/2016 ECE 264: Lecture 7 10 + 123 Output:

11. Padding ( fill, setfill ) Padding in a field  Fill characters are used to pad a field Member function fill  Specifies the fill character  Spaces are used if no value is specified  Returns the prior fill character Stream manipulator setfill  Specifies the fill character 1/10/2016 ECE 264: Lecture 7 11

12. Example 8: setfill, setw // Fig. 15.16: Fig15_16.cpp // Using member-function fill and stream-manipulator setfill to change // the padding character for fields larger than the printed value. #include using std::cout; using std::dec; using std::endl; using std::hex; using std::internal; using std::left; using std::right; using std::showbase; #include using std::setfill; using std::setw; 1/10/2016 ECE 264: Lecture 7 12

13. Example 8: 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; // 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 1/10/2016 ECE 264: Lecture 7 13

14. Example: setfill, setw (output) 1/10/2016 ECE 264: Lecture 7 14

15. WCT (Writing Code Together) Session Write a program that converts integer Fahrenheit temperatures from 0 to 212 degrees to floating-point Celsius temperatures with 3 digits of precision. Use the formula celsius = 5.0 / 9.0 * ( fahrenheit - 32 ); to perform the calculation. The output should be printed in two right-justified columns and the Celsius temperature should be preceded by a sign for both positive and negative values 1/10/2016 ECE 264: Lecture 7 15

16. WCT Session Expected output 1/10/2016 ECE 264: Lecture 7 16

17. WCT Session 1/10/2016 ECE 264: Lecture 7 17

18. Final notes Next time Introduce classes Acknowledgements: this lecture borrows heavily from lecture slides provided with the following texts: Deitel & Deitel, C++ How to Program, 8 th ed. Etter & Ingber, Engineering Problem Solving with C++, 2 nd ed. 1/10/2016 ECE 264: Lecture 7 18