Python While Loops 🔄

Repeating Code

Python has two primitive loop commands: while loops and for loops. With the while loop we can execute a set of statements as long as a condition is true.

🥣 Analogy: Eating Cereal

Think of a while loop like eating a bowl of cereal.
While the bowl is not empty:
1. Take a spoonful.
2. Eat it.
3. Check if the bowl is empty again.
When the bowl is empty (Condition becomes False), you stop eating.

✨ Basic While Loop

python

i = 1
while i < 6:
  print(i)
  i += 1  # IMPORTANT: Increment i, or the loop will continue forever

🛑 Break and Continue

Break

Stop the loop even if the while condition is true.

python

i = 1
while i < 6:
  print(i)
  if i == 3:
    break
  i += 1

Continue

Stop the current iteration, and continue with the next.

python

i = 0
while i < 6:
  i += 1
  if i == 3:
    continue
  print(i)

🔚 The else Statement

With the else statement we can run a block of code once when the condition no longer is true.

python

i = 1
while i < 6:
  print(i)
  i += 1
else:
  print("i is no longer less than 6")

🎯 Real-World Application: Game Loop

Video games run inside a giant while loop that keeps running until the player quits.

python

game_over = False

while not game_over:
    player_action = input("Do you want to (p)lay or (q)uit? ")
    
    if player_action == "q":
        game_over = True
        print("Thanks for playing!")
    else:
        print("Playing game frame...")

✨ Pro Tip: "Do-While" Emulation

Python doesn't have a built-in do-while loop, but you can emulate it using while True and break.

python

while True:
    user_input = input("Type 'exit' to stop: ")
    if user_input == 'exit':
        break
    print(f"You typed: {user_input}")

⚠️ Infinite Loops

If you forget to update the variable used in the condition, the loop will run forever and crash your program. To stop an infinite loop in the terminal, press Ctrl + C.