COS 100: Introduction to Programming

Interim 2020

Lab 3: Using logic

In-class practice labs will not directly impact your grade (although you'll get your standard participation point for staying on task), and will serve to help you with homework projects.

Lab 3A: Wie finden Sie das Wetter?

• Goal: To get experience with nested if statements and compound conditional statements.
• Task: Ask the user if it is cold outside, then ask them if they are tired.
  • If it is cold and they are tired, tell them to stay inside and read a book.
  • If it is cold and they are not tired, tell them to go skiing.
  • If it is not cold and they are tired, tell them to take a nap outside.
  • If it is not cold and they are not tired, tell them to go running.
• You should try to write this program in two different ways:
  • Write it once with nested if statements with simple conditionals.
  • Write it again with non-nested if statements that use logical and and/or logical or operators to create more complicated conditionals.
• Hints:
  • Remember that strings in Python can be compared using ==.
  • Remember to give the user good prompts.

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Lab 3B: Do you know facts about my pet?

• Task: Ask the user for a type of pet and whether their pet is male or female. Then we will tell them facts about their pet.
• Ask the user only two questions total: "What type of animal is your pet?" and "Is your pet male or female?"
• We'll assume that the types of pets are: cat, dog, fish, bird, hamster, and snake.
• Facts you should give to the user if they select the appropriate animal:
  • cats, dogs, and hamsters are all mammals.
  • cats, dogs, and snakes eat meat.
  • hamsters are omnivores.
  • fish and snakes both have scales.
  • birds, hamsters, and snakes all live in cages.
  • female birds, fish, and snakes lay eggs.
• Only provide the fact if the animal the user provides fits in that category.
• For example, if the user says they have a snake that is female, you should tell them:
  • Snakes eat meat
  • Snakes have scales
  • Snakes live in cages
  • Female snakes lay eggs
• Challenge: Format your facts in a single sentence, like: "Female snakes eat meat, have scales, live in cages, and lay eggs." Can you always get the punctuation and the use of the word "and" correct no matter what the user says?
• Hint: You can use print("Tofu", end="") to print the word Tofu and stay on the same line for the next print statement.

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Challenge Lab 3C: Is there a better way to do this?

• This exercise can be completed using what we already know, but part of what you will discover is that there's plenty of room for improvement. We're going to learn a much better way of tackling this sort of problem next time.
• Task:
  • First, ask the user how many numbers they plan to type in.
  • If the user gives a number less than 1, or more than 10, your program should (politely) yell at them and then quit (use exit()).
  • Otherwise, collect as many floating point numbers as the user said they were going to enter, one at a time, prompting them for input each time as shown below.
  • Finally, tell the user what the average of those numbers is.
• Before moving on: Spend some time pondering how much repeated code you have, and how nice it would be to have a more compact way of accomplishing the same repeated behavior without having to repeat the code.
• Sample runs:

  How many numbers do you want to take the average of? (1-10) 23
  That's ridiculous!
  
  How many numbers do you want to take the average of? (1-10) 4
  Please enter your 1st number: 5.2
  Please enter your 2nd number: 10.46
  Please enter your 3rd number: 1
  Please enter your 4th number: 17.924
  Your average is 8.646