[Tutor] input python 3.3

[Peter Otten]

Ian D wrote:

> Hello
>  
> I used to use 2.7 and the input was pretty when inputting a numeric value,
> it would just get cast to an int.
>  
> Seems that 3.3 I have to cast each input so :
> float(num1 = input("Enter a number")

You mean

num1 = float(input("Enter a number"))

  
> Is this just they way it is now? Is there a way to get back to just
> typing:
>  num1 = input("Enter a number ")
>  in python 33.
>  
> Seems a backwards step unless (and am sure this is the case)it is
> beneficial in so many other ways?

input() in Python 2 did not just recognize numbers, it allowed you to 
evaluate an arbitrary Python expression. For example:

$ touch important_file
$ ls
important_file
$ python
Python 2.7.2+ (default, Jul 20 2012, 22:15:08) 
[GCC 4.6.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> input("Enter a number: ")
Enter a number: __import__("os").remove("important_file")
>>> 
$ ls

Oops, the file is gone. I'm sure you can see why this is dangerous. 
Therefore the recommendation for Python 2 is to use raw_input() instead of 
input() -- and for Python 3 raw_input() was renamed to the more obvious 
input().

You can get the old input() behaviour with

num1 = eval(input(...))

which is still dangerous, but makes the risk more obvious.