Exception Handling in Python (Try...Except)

Question

I'm trying to implement the try...except exception handling into the code below. When something like "s4" is entered, I want the output of "Non numeral value..." to appear.

Any idea on where I've gone wrong?

import string

import math

def getSqrt(n):
    return math.sqrt(float(n))

s = input("Enter a numerical value: ")

try:
    for i in s:
        if (i.isdigit() or i == "."):
            sType = "nonstr"

    if (sType =="nonstr"):
        print(getSqrt(s))

    else:
        s = "Non numberical value..."


except ValueError as ex:
    print(ex)


else:
    print(s)

Answer 1

Ask for forgiveness - convert the entered value to float and handle ValueError:

try:
    s = float(input("Enter a numerical value: "))
except ValueError:
    print("Non numberrical value...")
else:
    print(getSqrt(s))

Demo:

>>> try:
...     s = float(input("Enter a numerical value: "))
... except ValueError:
...     print("Non numberrical value...")
... 
Enter a numerical value: s4
Non numberrical value...