Do while loop in Python 3

Question

I wanted to have some sort of thing that if the user inputs "Quit", the program breaks. I think that I could achieve that with a do while loop but I don't understand how to implement it. Please help me.

num1 = float(input("Enter First Number: "))
num2 = float(input("Enter second number: "))
op = input("Enter Operator: ")

if op == "*":
    print(num1 * num2)

elif op == "+":
    print(num1 + num2)

elif op == "-":
    print(num1 - num2)

elif op == "/":
    print(num1 / num2)

elif op == "%":
    print(num1 % num2)

else:
    print("Invalid Operator")

Welcome to StackOverflow! I see you're a new contributor, so I advise you to check out [How to ask a good question](https://stackoverflow.com/help/how-to-ask), [How to create a minimal reproducible example](https://stackoverflow.com/help/minimal-reproducible-example), and [Why is "Can someone help me?" not an actual question?](https://meta.stackoverflow.com/a/284237/11082165). — Brian61354270, Apr 04 '21 at 15:39
https://stackoverflow.com/questions/23294658/asking-the-user-for-input-until-they-give-a-valid-response this might give you some kind of orientation — dot.Py, Apr 04 '21 at 15:42

score 1 · Answer 1 · answered Apr 04 '21 at 15:46

1

while True:
    try:
        #insert your "loop" here
        [.....]
        
    except ValueError:
        #restart the loop
        continue

    else:
        #exit the loop
        break

answered Apr 04 '21 at 15:46

dot.Py

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score 0 · Answer 2 · answered Apr 04 '21 at 15:49

while True:
    while True:
        num1 = input("Enter First Number: ")
        if num1.lower() == "quit":
            quit()
        try:
            num1 = int(num1)
            break
        except ValueError:
            print(f"{num1} is not an integer.")

    while True:
        num2 = input("Enter second number: ")
        if num2.lower() == "quit":
            quit()
        try:
            num2 = int(num2)
            break
        except ValueError:
            print(f"{num2} is not an integer.")

    op = input("Enter Operator: ")
    if op.lower() == "quit":
        quit()

    if op == "*":
        print(num1 * num2)
    elif op == "+":
        print(num1 + num2)
    elif op == "-":
        print(num1 - num2)
    elif op == "/":
        print(num1 / num2)
    elif op == "%":
        print(num1 % num2)
    else:
        print("Invalid Operator")

@BrainGym a `while` loop runs while a condition is met. In this case, `while True:` is effectively an infinite loop (`while True` will always be `True`). What I've done is have each step run until the input is valid, *or* until the user enters "quit." `break` will break the program out of the infinite loop. So this program runs each step until it receives a valid input or the user enters "quit." I recommend reading [ATBSWP Chapter 2](https://automatetheboringstuff.com/2e/chapter2/) for a more thorough explanation. — will-hedges, Apr 06 '21 at 18:49

Do while loop in Python 3

2 Answers2