[Solved] Python for Everybody - Chapter 5: Iteration

This tutorial gives you the solutions to the exercises in Chapter 5 of the book Python for Everybody: Exploring Data Using Python 3 by Charles R. Severance.

Link to the book:

• PDF
• Amazon

Solutions for other chapters:

• [Solved] Python for Everybody - Chapter 5: Iteration (this tutorial)
• [Solved] Python for Everybody - Chapter 6: Strings
• [Solved] Python for Everybody - Chapter 8: Lists

1. Chapter 5: Iteration - Exercise 1

Exercise 1: Write a program which repeatedly reads numbers until the user enters “done”. Once “done” is entered, print out the total, count, and average of the numbers. If the user enters anything other than a number, detect their mistake using try and except and print an error message and skip to the next number.

Answer:

total = 0
count = 0
average = 0

while True:
	number = input("Enter a number: ")

	try:
		number = float(number)

		total += number
		count += 1
	except:
		if number == "done":
			break
		else:
			print("Invalid input")
			continue

average = total / count
print(total, count, average)

Output:

Explanation:

1. while True means the loop will run forever until we use break to stop it.
2. We get the input from the user using input() function.
3. Use try/except to handle invalid numbers, i.e. the user enters anything other than a number.
4. If the user enters done, we use break to stop the loop.
5. Otherwise, we add the number to total and increase count by 1.
6. Finally, we calculate the average and print out the result.

2. Chapter 5: Iteration - Exercise 2

Exercise 2: Write another program that prompts for a list of numbers as above and at the end prints out both the maximum and minimum of the numbers instead of the average.

Answer:

total = 0
count = 0
maximum = None
minimum = None

while True:
	number = input("Enter a number: ")

	try:
		number = float(number)

		if maximum is None or number > maximum:
			maximum = number

		if minimum is None or number < minimum:
			minimum = number

		total += number
		count += 1
	except:
		if number == "done":
			break
		else:
			print("Invalid input")
			continue

print(total, count, maximum, minimum)

Output:

Explanation:

1. while True means the loop will run forever until we use break to stop it.
2. We get the input from the user using input() function.
3. Use try/except to handle invalid numbers, i.e. the user enters anything other than a number.
4. If the user enters done, we use break to stop the loop.
5. Otherwise, we add the number to total and increase count by 1, then we update the maximum and minimum values.
6. Finally, we calculate the average and print out the result.

Conclusion

In this tutorial, we have solved 2 problems of the Chapter 5: Iteration in the book Python for Everybody: Exploring Data Using Python 3.

Please leave a comment if you have any questions.