While(!EOF()) equivalent in Python

Question

I'm working on a school project and it specifically asks for a while not end-of-file loop which I don't know how to do in Python. I'm taking in user input (not from an external file) and computing some math in this infinite loop until they CTRL+C to break the loop. Any thoughts would really help me out. I've added part of the instruction if that helps clarify. Thanks.

Answer 1

Your loop is supposed to stop on two conditions:

• An illegal value was entered, ie some value that couldn't be converted to a float. In this case, a ValueError will be raised.

• You entered ctrl-Z, which means an EOF. (Sorry, having no Windows here, I just tested it on Linux, where I think that ctrl-D is the equivalent of the Windows ctrl-Z). An EOFError will be raised.

So, you should just create an infinite loop, and break out of it when one of these exceptions occur.

I separated the handling of the exceptions so that you can see what happens and print some meaningful error message:

while True:
    try:
        amount = float(input())
        print(amount) # do your stuff here
    except ValueError as err:
        print('Terminating because', err)
        break
    except EOFError:
        print('EOF!')
        break

If you just want to quit without doing anything more, you can handle both exceptions the same way:

while True:
    try:
        amount = float(input())
        print(amount) # do your stuff here
    except (ValueError, EOFError):
        break

Answer 2

Use the following:-

while True:
    amount = raw_input("Dollar Amount: ")
    try:
        amount = float(amount)
        # do your calculation with amount
        # as per your needs here

    except ValueError:
        print 'Cannot parse'
        break