Conditions

while loops use conditions just like if statements. You can use operators to compare values in or to generate True or False conditions. Looping until a condition is met can be useful when you are getting getting input from a user, generating random variables, or repeatedly applying a transformation to a value.

user_input = -1
while user_input < 1 and user_input > 10:
    user_input = input("Tell me a number between 1-10 (inclusive): ")

While True / Break

You can also make while loops run indefinitetly by setting the condition to True like this: while True:. This can be useful when you want to loops a program repeatedly.

To stop a loop like this, you can use a break statement. Once the program reaches the break, the loop will exit.

You’ve actually already seen an example of this kind of loop at the beginning of the lab.

speed(10)
while True:
    drawing = input("What would you like me to draw? ")
    size = int(input("How big should I draw it? "))
    if drawing == "square":
        for i in range(4):
            forward(size)
            right(90)
    elif drawing == "quit":
        break
    else:
        print("Sorry, I don't know how to draw that...")