[Tutor] Stuck on some basics re floats

[Peter Otten]

Matthew Polack wrote:

> Hi,
> 
> I'm a teacher trying to learn Python with my students.
> 
> I am trying to make a very simple 'unit calculator' program...but I get an
> error ..I think python is treating my num1 variable as a text string...not
> an integer.
> 
> How do I fix this?
> 
> Thanks!
> 
> - Matt
> 
> print ("How many inches would you like to convert? ")
> num1 = input('Enter inches here')

As you have guessed, at this point num1 is a string. You can convert it to a 
float with

num1 = float(num1)

> print ("You have entered",num1, "inches")
> convert = num1 * 2.54
> print ("This is", convert, "centimetres")
> 
> 
> Traceback (most recent call last):
>   File "convert.py", line 10, in <module>
>     convert = num1 * 2.54
> TypeError: can't multiply sequence by non-int of type 'float'

Note that int is mentioned here because Python can multiply int with str, 
though the result might surprise you:

>>> "spam" * 3
'spamspamspam'

So * also works as the repetition-operator just like + is also used to 
concat strings.