Basic Overview

  • A while loop is a programming structure that allows us to execute a block of code repeatedly as long as a condition is true.
  • This can be particularly useful for counting or accumulating values.
  • In this example, we will use a while loop to display messages a specific number of times.
# count ← 1
# increasing ← TRUE
#
# WHILE increasing IS TRUE:
#     DISPLAY count
#     count ← count + 1
#     IF count IS GREATER THAN 5:
#         increasing ← FALSE
# END WHILE
#
# WHILE increasing IS FALSE:
#     count ← count - 1
#     DISPLAY count
#     IF count IS EQUAL TO 1:
#         increasing ← TRUE
# END WHILE


i = 1  # Start counting from 1
increasing = True  # Initialize the boolean flag

# Count up from 1 to 5
while increasing:
    print(i)
    i += 1
    if i > 5:
        increasing = False  # Stop increasing once 5 is reached

# Count down from 5 to 1
while not increasing:
    i -= 1
    print(i)
    if i == 1:
        increasing = True  # Reset once 1 is reached

#Problem:
#Use a boolean value to indefinitely print a string, or a message of your personal choice.



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What’s Happening:

  • A while loop is a control structure that allows us to execute a block of code repeatedly as long as a specified condition is true.
  • In this example, we start with a variable count set to 1 and continue looping until count exceeds 3.
  • Each time the loop executes, it displays a message that includes the current value of count and then increments count by 1.
  • This method can be useful for tasks like counting, accumulating values, or running a block of code until a certain condition changes.
  • If the condition never changes (e.g., if the loop’s terminating condition is never met), it can lead to an infinite loop, which continuously runs the code without stopping.

Additional Notes:

  • Infinite Loop: It’s important to ensure that the condition in the while loop will eventually become false; otherwise, you may create an infinite loop that never stops running.
  • Control Flow: While loops can help manage the flow of your program, especially in cases where you do not know in advance how many times you need to repeat a task.
  • Common Use Cases: While loops are often used in scenarios like reading data until the end of a file, processing user input until a specific command is given, or performing actions until a desired outcome is achieved.