I am writing a program that needs to check if a users input is a decimal (the users input must be a deciamal number),I was wondering how I could test a varible to see if it contains only a decimal number.
Thanks, Jarvey
6 Answers
U also could use a Try/Except to check if the variable is an integer:
try: val = int(userInput) except ValueError: print("That's not an int!") or a float:
try: val = float(userInput) except ValueError: print("That's not an float!") 
3 Comments
hpj
Hi, thanks for the help, this one seemed to work but it also allows charaters and I want is float numbers, do you have any idea how I could stop characters begin accepted?
Stan Vanhoorn
How do you mean? If I type in anything other than a number it raises the exception. So in this case it prints: That's not an float!
Jeyekomon
Be aware that
int(12.3) also works fine but 12.3 is a float, not an integer.You can use float.is_integer() method.
Example: data = float(input("Input number"))
if data.is_integer(): print (str(int(data)) + ' is an integer') else: print (str(data) + ' is not an integer') 
Comments
I found a way of doing this in python but it doesn't work in a new window/file.
>>> variable=5.5 >>> isinstance(variable, float) True >>> variable=5 >>> isinstance(variable, float) False I hope this helped.
Comments
You can use isinstance:
if isinstance(var, float): ... 
1 Comment
hpj
when I do this it will not allow a decimal number but will allow text. what is a way that I can only allow a decimal number like '0.2' or '1.5' to be accepted but an input like 'hello' will be rejected?
(one) fast anwer
a=1 b=1.2 c=1.0 d="hello" l=[a,b,c,d] for i in l: if type(i) is float: print(i) #result : 1.0, 1.2 long answer : What's the canonical way to check for type in python?
5 % 1 == 0and5.25 % 1 = 0.25