Using isdigit for floats?

Question

a = raw_input(\'How much is 1 share in that company? \')

while not a.isdigit():
    print(\"You need to write a number!\\n\")
    a = raw_input(\'How much is 1 shar         


        

Answer 1

Building on dan04's answer:

def isDigit(x):
    try:
        float(x)
        return True
    except ValueError:
        return False

usage:

isDigit(3)     # True
isDigit(3.1)   # True
isDigit("3")   # True
isDigit("3.1") # True
isDigit("hi")  # False

Answer 2

The existing answers are correct in that the more Pythonic way is usually to try...except (i.e. EAFP).

However, if you really want to do the validation, you could remove exactly 1 decimal point before using isdigit().

>>> "124".replace(".", "", 1).isdigit()
True
>>> "12.4".replace(".", "", 1).isdigit()
True
>>> "12..4".replace(".", "", 1).isdigit()
False
>>> "192.168.1.1".replace(".", "", 1).isdigit()
False

Notice that this does not treat floats any different from ints however. You could add that check if you really need it though.