While Loops

A while loop repeats as long as a specific condition is True, making it ideal for situations where we don't know the iteration count in advance. Always ensure the loop condition eventually becomes False to avoid an infinite loop.

Basic Repetition​

while loops in Python work exactly as we'd expect. We can use continue to skip the rest of the current iteration and jump back to the condition check.

count = 1
while count <= 3:
    print(f"Loop iteration: {count}")
    count += 1

Output:

Loop iteration: 1
Loop iteration: 2
Loop iteration: 3

Validation Loops: "Ask Until Valid"​

A common Pythonic pattern is to use while True combined with break to loop forever until the user provides correct data.

allowed_options = {"yes", "no", "maybe"}

while True:
    choice = input("Enter yes/no: ").strip().lower()

    if choice in allowed_options:
        print(f"We chose: {choice}")
        break  # Exit the loop entirely

    print(f"Invalid choice. Please choose from: {allowed_options}")

Output:

Enter yes/no: okay
Invalid choice. Please choose from: {'maybe', 'no', 'yes'}
Enter yes/no: yes
We chose: yes

Why Use while True?​

Using while True with an internal break is often cleaner than initializing a dummy variable just to satisfy a condition. It keeps the "ask" logic and the "exit" logic clearly separated.