Python exercises: Loops¶

Note Some of the exercises below are adapted from the Python for Everyone Course by Charles R. Severance licensed under Creative Commons Attribution 3.0

Exercise 1. Print total, count, and average¶

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.

Enter a number: 4
Enter a number: 5
Enter a number: 7
Enter a number: done
16 3 5.333333333333333

# your code here

Exercise 2. Print total, count, and average and check incorrect inputs¶

Now adapt the code in Exercise 1 and 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.

Enter a number: 4
Enter a number: 5
Enter a number: bad data
Invalid input
Enter a number: 7
Enter a number: done
16 3 5.333333333333333

# your code here

Exercise 3. Print maximum and minimum¶

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.

# your code here

Exercise 4. Print moving text¶

Write a program that prints Hello world repeatedly (40 times) to the screen and is preceded by a string called “fill” that adds a space to itself each time the loop is repeated. You should see the text Hello world moving to the right of the screen. Refresh the loop each ~500 ms (0.5 seconds). For this you might want to make use of the python time module.

Note that you need the range function for this exercise that creates a list of numbers you loop over. You will learn more about list objects during a later chapter in this course.

To make sure that the print replaces the previous print try this (running this in Spyder might give better results than Colab):

print('\r','your text here',end='')

# your code here

Exercise 5. Printing a Christmas tree¶

Complete the print_tree() function below to print a Christmas tree made out of asterisks. The function takes a single parameter, height, which represents the height of the tree. Print spaces before the asterisks to center the tree.

Test the function with different values for the height.

E.g. print_tree(5) should return:

    *
   ***
  *****
 *******
*********

and print_tree(10) should return:

         *
        ***
       *****
      *******
     *********
    ***********
   *************
  ***************
 *****************
*******************

def print_tree(height):
    # Loop through the rows of the tree
    for row in range(height):
        # your code here
        print("something to edit by you")

Experimentation 1

Python exercises: Loops

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