Decimals

[Steve Holden]

Tgone wrote:
> Sybren Stuvel wrote:
> 
>>Tgone enlightened us with:
>>
>>>Sorry, when I print out the variable it displays as '15.0'. The
>>>price is '15.00' in the database though.
>>
>>That's the same thing, isn't it? 15.0 == 15.000000000
> 
> 
> Yes, they're both mathematically the same. I never said they weren't...
> 
> 
>>>Here's my code:
>>>
>>>product = Product.get(2)
>>>print product.price # 15.0
>>
>>Try string formatting:
>>
>>print '%.2f' % product.price
> 
> 
> That works. I expected Python to display the data exactly as it is in
> the database, like most languages.
> 
Well I'm sorry Python doesn't live up to your expectations, but I think 
your assertion "like most languages" is a little over-reaching.

What's actually happening is that the database is storing the number in 
some internal format known to itself. The module you are using to access 
the database is actually converting that value to a floating-point 
number (I'm guessing here: some more modern modules will convert it to a 
decimal). That's where the scaling factor gets lost, as until fairly 
recently Python only *had* floats (well, and complex numbers)to 
represent non-integral numbers.

So basically you are likely to be stuck with formatting the data the way 
you want to see it. This is fairly usual in my experience.

regards
  Steve
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