Data type and its size

[zkl]

Hi,

Can someone explain to me this data type and size.

double denominator, numerator, result;

Is it about having these numbers in decimals and not whole numbers?
Thanks =D

[Aramil of Elixia]

its just double the size of floats

[zkl]

Thats all?

[Anthony Hernandez]

yup.

http://www.cplusplus.com/doc/tutorial/variables/

I try to stick with either just floats or just doubles when writing a program.

[Stewbond]

I believe you're asking about integer division.

1 2 3 4 5

int a = 5, b = 2; cout << a/b << endl; double c = 5, d = 2; cout << c/d << endl;

2 2.5

If you divide doubles or floats, you're going to get the decimal. If you divide floats, you're going to get a whole number. That's it.

[Stewbond]

@Anthony
That works if you are just doing calculations, but what about conditional statements?

if (a == 1.0)
is never a good idea because floats rarely "equal" a desired number. They can be infinitely close, but an equal sign just won't work 99 percent of the time. You'd need to do something like: if (a > 0.99 && a < 1.01) but that gets annoying and verbose. Something like this will almost guarentee an infinite loop:
for (float i = 0.f; i != 100.f; i += 0.1f) { /*do something*/ }

ints are great for switch statements, conditional statements, counting, or math where you need to know precision and cant afford to loose any digits (such as banking software).

[Anthony Hernandez]

@Stewbond

That's true. It's hard to account for precision loss when dealing with floating points.

I was working on some homework and the book I'm reading had this to account for the precision loss:

#define EPSILON 0.000001

// Other code...

//add in a small amount to cover any precision errors we may have made
m_dBestPossibleRoute += EPSILON; 

[zkl]

Thanks for the explanations :)