How do you check if input is numerical in Python?

Question

I have written a script in Python and I want to make it so if you don't input a number when it asks "What's your age?" It will say "Please input a number" and then repeat the original question. I have tried many different suggestions I have seen on other posts but none of them are working.

Here is the script:

yesorno = "yes"

while yesorno == "yes" :
    import time
    Age = 0
    Age = int(input("What is your age?"))
    Age = Age*365*24
    print(Age)
    yesorno = input("Would you like to run again?(yes/no)")

while yesorno != "no" :    
print("Please input yes or no")
yesorno = input("Would you like to run again?(yes/no)")

while yesorno == "no" :
print("Program stopping...")
import sys
sys.exit("Program stopping...")

There are also plenty of postings to show you how to loop until the input is valid. — Prune, Nov 10 '17 at 17:50

score 0 · Accepted Answer · answered Nov 10 '17 at 17:39

There are many ways to do this, but allow me to recommend one that adds to your existing code, focusting on this line:

Age = int(input("What is your age?"))

As you probably already know, if the person inputs something that isn't an integer, this line throws an error.

You can catch these errors in a try...except... block, excepting the error that's thrown when any non-int is inputted in that line.

try:
    Age = int(input("What is your age?"))
except ValueError:
    print("Please input a number")

To make this continue the loop, I'd put the yesorno in the try statement so it only executes if the Age input was successful, otherwise, react as if the user inputted yes, as so:

 try:
    Age = int(input("What is your age?"))
    Age = Age*365*24
    print(Age)
    yesorno = input("Would you like to run again?(yes/no)")
except ValueError:
    print("Please input a number")
    yesorno = "yes"

How do you check if input is numerical in Python?

1 Answers1