1 / 26

Announcements

Announcements. I have not graded your exam yet. Multiple Alternative Ifs. if (condition1) statement1; else if (condition2) statement2; … else defaultstatement;. Program. Write a program that displays a letter grade corresponding to an exam score 90 - 100 A 80 - 89 B 70 - 79 C

tuyet
Download Presentation

Announcements

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Announcements • I have not graded your exam yet CS150 Introduction to Computer Science 1

  2. Multiple Alternative Ifs if (condition1) statement1; else if (condition2) statement2; … else defaultstatement; CS150 Introduction to Computer Science 1

  3. Program • Write a program that displays a letter grade corresponding to an exam score 90 - 100 A 80 - 89 B 70 - 79 C 60 - 69 D 0-59 F CS150 Introduction to Computer Science 1

  4. Example if (salary < 0.00) tax = -1; else if (salary < 15000.00) tax = 0.15 * salary; else if (salary < 30000.00) tax = (salary - 15000.00)*0.16 + 2250.00; else tax = salary * 0.26; CS150 Introduction to Computer Science 1

  5. if (x >= 0) x = x + 1; else if (x >= 1) x = x + 2; if (x >= 0) x = x + 1; if (x >= 1) x = x + 2; What’s the difference? CS150 Introduction to Computer Science 1

  6. Selection Structure Review • Write a program to solve the following problem: A police department needs to calculate fees for speeding tickets. The fees are as follows: Speed Fee 75 or greater $60.00 51 - 74 $40.00 36 - 50 $20.00 CS150 Introduction to Computer Science 1

  7. Switch Statements • Another form of selection statement • Similar to if’s • Useful for lots of alternatives CS150 Introduction to Computer Science 1

  8. Example switch (watts) { case 25: life = 2500; break; case 40: case 60: life = 1000; break; case 75: case 100: life = 750; break; default: life = 0; } CS150 Introduction to Computer Science 1

  9. Form switch (selector) { case label1: statements1; break; case label2: statements2; break; … case labeln: statementsn; break; default: statements; } CS150 Introduction to Computer Science 1

  10. switch (musical_note) { case ‘c’: cout << “do” << endl; break; case ‘d’: cout << “re” << endl; break; case ‘e’: cout << “mi” << endl; break; case ‘f’: cout << “fa” << endl; break; case ‘g’: cout << “sol” << endl; break; case ‘a’: cout << “la” << endl; break; case ‘b’: cout << “ti” << endl; break; default: cout << “An invalid note was read.”; } Example CS150 Introduction to Computer Science 1

  11. Important! • Selector must be ordinal type • Each possible value is a separate case • break stops statements for case, otherwise continue with statements for next case CS150 Introduction to Computer Science 1

  12. Example switch (color) { case ‘R’: case ‘r’: cout << “red” << endl; case ‘B’: case ‘b’: cout << “blue” << endl; case ‘Y’: case ‘y’: cout << “yellow” << endl; } What happens when color is ‘r’? ‘B’? ‘Y’? CS150 Introduction to Computer Science 1

  13. Example switch (x > y) { case 1: cout << “x greater” << endl; break; case 0: cout << “y greater or equal” << endl; break; } Write as if statement CS150 Introduction to Computer Science 1

  14. Questions • Can you write any switch statement as an if? • Can you write any if statement as a switch? CS150 Introduction to Computer Science 1

  15. Problem • Write a switch statement to convert a character digit to an integer CS150 Introduction to Computer Science 1

  16. Change to switch if (speed > 35) fee = 20.00; else if (speed > 50) fee = 40.00; else if (speed > 75) fee = 60.00; CS150 Introduction to Computer Science 1

  17. Examples • Write an if statement that prints out the level of schooling. (0, none; 1 through 6, elementary; 7 through 8, middle school; 9 through 12, high school; > 12, college) • Write a switch statement to do the same CS150 Introduction to Computer Science 1

  18. Write a Program Input an integer If the integer is positive, increment a variable poscount by 1. If the integer is negative, increment a variable negcount by 1. If neither, increment zerocount by 1. CS150 Introduction to Computer Science 1

  19. Unary Operators ++ and -- • ++ is increment operator x++; is the same as x = x + 1; • -- is decrement operator x--; is the same as x = x - 1; CS150 Introduction to Computer Science 1

  20. Prefix and PostfixUnary ++ and -- Prefix Postfix k = --x; k =x--; k = ++x; k = x++; Increment/ Assign value of x to decrement x k, then increment then assign or decrement x value of x to k CS150 Introduction to Computer Science 1

  21. Example cout << “Value of i is” << i; cout << “Value of i++ is” << i++; cout << “Value of ++i is” << ++i; cout << “Value of --i is” << --i; cout << “Value of i-- is” << i--; CS150 Introduction to Computer Science 1

  22. Program • Write a program that outputs the following: ***** ***** ***** ***** ***** CS150 Introduction to Computer Science 1

  23. Loops Initialize LCV count = 0; while (count < 5) { cout << “*****” << endl; count++; } How many times (iterations) does loop run? Loop Control Variable Change the value of count CS150 Introduction to Computer Science 1

  24. While loops while (logical expression is true) statement; while (logical expression is true) { statement1; statement2; … } CS150 Introduction to Computer Science 1

  25. Key ingredients • Initialize MUST initialize loop control variable • Test The value of loop control variable is tested during each iteration of loop • Update Loop control variable is changed during each loop iteration If any one of these is missing or incorrect, your loop won’t run properly--not at all, too many/few times or infinitely. CS150 Introduction to Computer Science 1

  26. Examples • Write a while loop that outputs each integer from 1 to 5 • Write a program that inputs the following data for 5 students: name, id# and grade • Write a program that inputs the following data for a user specified number of students: name, id# and grade CS150 Introduction to Computer Science 1

More Related