Is there a better way of making sure a variable only contains numbers

Question

toss_number = input("How many times do you want to toss the coin?\n")

while True:
    if toss_number.isdigit():
        break
    else:
        toss_number = input("Please input NUMBER of times you want to toss a coin.\n")

These lines of code essentially make sure that toss_number contains a string of numbers. Is there a better/more efficient way of doing this?

Other ways to approach this problem: https://stackoverflow.com/questions/23294658/asking-the-user-for-input-until-they-give-a-valid-response — Mr. T, May 25 '18 at 21:45

jpp · Accepted Answer · 2018-05-25T22:25:24.697

1

An alternative way is to use try / except. This will be more efficient if, more often than not, a number is input.

while True:
    try:
        toss_number = int(input("How many times do you want to toss the coin?\n"))
        break
    except ValueError:
        print('You have not entered a NUMBER.')

When ValueError is raised, a message is printed, but the loop is not broken, so we return to beginning of the while loop and the try section.

edited May 25 '18 at 22:25

answered May 25 '18 at 21:46

jpp

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Why are we able to put `break` before `except ValueError`? – StrangeRanger May 25 '18 at 22:10
I just thought that you would want to put the break after `except ValueError`, or add an `else: break` statement to the end of the while statement. – StrangeRanger May 25 '18 at 22:18
So is the fact that a `ValueError` is raised, prevent `break` from breaking the while loop? – StrangeRanger May 25 '18 at 22:22

Is there a better way of making sure a variable only contains numbers

1 Answers1