Basic Overview:

  • A while loop is a control structure that repeatedly executes a block of code as long as a specified condition remains true.
  • This type of loop is particularly useful for tasks like counting, accumulating values, or continuing until a particular condition is met.
  • In this lesson, the while loop is demonstrated to display a message with a count from 1 to 3.
# In this example, we will use a while loop to display letters from 'A' to 'E' and calculate their corresponding ASCII values.

# Pseudocode:
# count ← 1
# WHILE count IS LESS THAN OR EQUAL TO 3:
#     DISPLAY "This is message number" count
#     count ← count + 1
# END WHILE


# Python Code:
count = 1  # Start counting from 1
while count <= 3:  # Continue while count is 3 or less
    print("This is message number", count)  # Display the current message number
    count += 1  # Increment count by 1

#Problem: Infinite Loop with a While Statement
#Write a while loop that continuously prints "Hello, World!" until you stop the program.


This is message number 1
This is message number 2
This is message number 3

What’s Happening:

  • We start with the variable count set to 1.
  • The loop checks if count is less than or equal to 3, and as long as this condition is true, the code inside the loop runs.
  • On each iteration, the current message number is printed, and count is incremented by 1.
  • Once count exceeds 3, the condition becomes false, and the loop terminates.

Additional Notes:

  • Infinite Loops: Care must be taken to ensure that the condition in the loop will eventually become false; otherwise, it could result in an infinite loop that never stops.
  • Practical Use Cases: While loops are great for situations where the number of iterations isn’t known ahead of time, like reading data until the end of a file or waiting for specific user input.
  • Common Pitfall: A common mistake is forgetting to update the loop control variable (like count in this case), which can cause an infinite loop if the condition never becomes false.