A while loop in Python repeatedly executes a block of code as long as a given condition is true. It’s often used when the number of iterations is unknown beforehand.
Syntax:
Python
while condition:
# code to be executed
Example:
Python
count = 0
while count < 5:
print(count)
count += 1
Key Points
- The condition is checked before each iteration.
- The loop continues as long as the condition evaluates to
True. - Be cautious of infinite loops if the condition never becomes
False.
Common Use Cases
- User input validation
- Iterating until a specific condition is met
- Game loops
Example: User Input Validation
Python
number = 0
while number <= 0:
number = int(input("Enter a positive number: "))
if number <= 0:
print("Invalid input. Please enter a positive number.")
print("You entered:", number)How is a while loop different from a for loop?
A for loop iterates over a sequence, while a while loop continues as long as a condition is true.
How do I ensure a while loop eventually terminates?
Make sure the loop condition will eventually become false
Can I use a break statement in a while loop?
Yes, to exit the loop prematurely.
Can I use a continue statement in a while loop?
Yes, to skip the current iteration and move to the next.
What is an infinite loop?
An infinite loop occurs when the loop condition never becomes false, causing the program to run indefinitely.
How can I prevent infinite loops?
Ensure that the loop’s condition will eventually change to False.