numbers

the thing is that, the 1st number is already ORACLE LONG, second one a Date (SQL DATE, no timestamp info extra), the last one being a Short value in the range 1000-100'000. how can I create sort of hash value that will be unique for each combination optimally? string concatenation and converting to long later: I don't want this, for example. Day Month 12 1 --> 121 1 12 --> 121 lapo When you have a few numeric values and need to have a single "unique" (that is, statistically improbable duplicate) value out of them you can usually use a formula like: h = (a*P1 + b)*P2 + c where P1 and P2 are

How do I convert a positive Integer to a negative with Delphi? I know you could use ABS(int) to convert a negative to a positive, but I need it to convert positive to negative. from what I know there is no function for that. you can make if yourvariable > 0 then yourvariable := -yourvariable; If you want to be absolutely sure to get a negative result (or zero), use number := -abs(number) Ehhh... Too late but number := number * -1; would work too, but this change the symbol of any number, negative to positive and backwards... To ensure a negative value go with @Mef Answer EDIT: even later, but

I want to print invoices for customers in my app. Each invoice has an Invoice ID . I want IDs to be: Sequential (ids entered lately come late) 32 bit integers Not easily traceable like 1 2 3 so that people can't tell how many items we sell. An idea of my own: Number of seconds since a specific date & time (e.g. 1/1/2010 00 AM). Any other ideas how to generate these numbers ? Vadim I don't like the idea of using time. You can run into all sorts of issues - time differences, several events happening in a single second and so on. If you want something sequential and not easily traceable, how

I would like a clear explanation of Num , Real , Integral , Integer , Int , Ratio , Rational , Double , Float . Thomas M. DuBuisson This answer mostly assumes you know the difference between types and type classes. If that difference is hazy to you then clear up your understanding there before reading on. Num Num is a typeclass that includes all numeric types. :info Num class Num a where (+) :: a -> a -> a (-) :: a -> a -> a (*) :: a -> a -> a negate :: a -> a abs :: a -> a signum :: a -> a fromInteger :: Integer -> a -- Defined in ‘GHC.Num’ instance Num Word -- Defined in ‘GHC.Num’ instance

I'm reading the Number Type section of the book Professional JavaScript for Web Developers . It seems to say that all ECMAScript numbers are binary64 floating point, which is corroborated by this MDN article . But the book author also says: Because storing floating-point values uses twice as much memory as storing integer values, ECMAScript always looks for ways to convert values into integers. I expected numbers to each occupy the same amount of memory: 64 bits. And the MDN article says, "There is no specific type for integers". Anyone know what the book author meant? How can integers take up