An Introduction To Python - Nested Branches, Multiple Alternatives
Download as PPTX, PDF1 like420 views
This document discusses nested conditional statements, multiple alternatives, and elif statements in Python. It provides examples of nested if/else statements to check for appointment overlaps and determine club entry. It explains that nested branches can be difficult to read and proposes using elif statements instead of excessive nesting. The document concludes by previewing while loops for the next session.
Ad
More Related Content
Viewers also liked (8)
Similar to An Introduction To Python - Nested Branches, Multiple Alternatives (20)
Ad
Recently uploaded (20)
Ad
An Introduction To Python - Nested Branches, Multiple Alternatives
- 1. An Introduction To Software Development Using Python Spring Semester, 2015 Class #6: Nested Branches, Multiple Alternatives
- 2. Sample “IF” Problem In a scheduling program, we want to check whether two appointments overlap. For simplicity, appointments start at a full hour, and we use military time (with hours 0–24). Image Credit: www.clipartpanda.com
- 3. “Hand Tracing” • Hand Tracking is a technique that you can use in order to determine if your program is working correctly. • Mentally execute your program’s statements and keep track of the value of each variable. Image Credit: www.clipartbest.com
- 4. Example: Let’s Talk About Taxes Federal Tax Rate Schedule Image Credit: www.clipartpanda.com
- 5. Hand Tracing The Tax Program Tax 1 Tax 2 Income Marital Status 80000 m
- 6. Hand Tracing The Tax Program Tax 1 Tax 2 Income Marital Status 0 0 8000 m
- 7. Hand Tracing The Tax Program Tax 1 Tax 2 Income Marital Status 0 0 8000 m 6400 4000 XXX XXX
- 8. Hand Tracing The Tax Program Tax 1 Tax 2 Income Marital Status 0 0 8000 m 6400 4000 10400 XXX XXX
- 9. What Is A “Nested Branch”? • It is often necessary to include an if statement inside another. Such an arrangement is called a nested set of statements. • Example: Is the club full? Arrive at the club Are you on the VIP list? Wait in car Go right in Wait in line Y Y N N
- 10. Example of a “Nested Branch” if (peopleInClub < maxPeopleInClub) : if (youName == VIPListName) : goRightIn else : waitInLine else : waitInCar
- 11. Multiple Alternatives • What should you do when you have to make a decision with more than one alternative? • Example: Telling a student what their grade in a class was…
- 12. Example: Telling Students What Their Grade In A Course Is If (classScore >=90) : print(“You got an A!”) else: if (classScore >= 80) : print(“You did ok, you got a B!”) else: if (classScore >=70) : print(“So-so, you got a C”) else: if (classScore >= 60) : print(“Oh –oh, you got a D”) else : print(“Dang it, you got an F”) Image Credit: jghue.blogspot.com
- 13. Problems With “Super Nesting” • Difficult to read • Shifted too far to the right due to indentation Image Credit: www.clipartbest.com
- 14. A Better Way: elif If (classScore >=90) : print(“You got an A!”) elif (classScore >= 80) : print(“You did ok, you got a B!”) elif (classScore >=70) : print(“So-so, you got a C”) elif (classScore >= 60) : print(“Oh –oh, you got a D”) else : print(“Dang it, you got an F”) Image Credit: jghue.blogspot.com Note that you have to test the more specific conditions first.
- 15. Example: Supermarket Coupons A supermarket awards coupons depending on how much a customer spends on groceries. For example, if you spend $50, you will get a coupon worth eight percent of that amount. The following table shows the percent used to calculate the coupon awarded for different amounts spent. Write a program that calculates and prints the value of the coupon a person can receive based on groceries purchased.
- 16. What’s In Your Python Toolbox? print() math strings I/O IF/Else elif
- 17. What We Covered Today 1. Hand Tracing 2. Nested Branch 3. elif Image Credit: http://www.tswdj.com/blog/2011/05/17/the-grooms-checklist/
- 18. What We’ll Be Covering Next Time 1. While Loop Image Credit: http://merchantblog.thefind.com/2011/01/merchant-newsletter/resolve-to-take-advantage-of-these-5-e-commerce-trends/attachment/crystal-ball-fullsize/
Editor's Notes
- #2: New name for the class I know what this means Technical professionals are who get hired This means much more than just having a narrow vertical knowledge of some subject area. It means that you know how to produce an outcome that I value. I’m willing to pay you to do that.