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alphacyberranger @lemmy.world

2y ago

Java

77 comments

Makes sense, cause double can represent way bigger numbers than integers.
- Also, double can and does in fact represent integers exactly.
  
  Only to 2^54. The amount of integers representable by a long is more. But it can and does represent every int value correctly
- Also because if you are dealing with a double, then you're probably dealing with multiple, or doing math that may produce a double. So returning a double just saves some effort.
- Yeah it makes sense to me. You can always cast it if you want an int that bad. Hell just wrap the whole function with your own if it means that much to you
  (Not you, but like a hypothetical person)
- A double can represent numbers up to +- 1.79769313486231570x10^308, or roughly 18 with 307 zeroes behind it. You can't fit that into a long, or even 128 bits. Even though rounding huge doubles is pointless, since only the first dozen digits or so are saved, using any kind of Integer would lead to inconsistencies, and thus potentially bugs.
  
  doubles can hold numbers way larger than even 64-bit ints
  
  A double could also be NaN and any operations with NaN should return NaN afaik
- How does that work? Is it just because double uses more bits? I'd imagine for the same number of bits, you can store more ints than doubles (assuming you want the ints to be exact values).
  
  No, it has an exponent component: https://en.m.wikipedia.org/wiki/Double-precision_floating-point_format

It's the same in the the standard c library, so Java is being consistent with a real programming language…
- Implying java isn't a real programming language. Smh my head.
  
  Java has many abstractions that can be beneficial in certain circumstances. However, it forces a design principle that may not work best in every situation.
  I.e. inheritance can be both unnatural for the programmer to think in, and is not representative of how data is stored and manipulated on a computer.
  
  Java is, of course, Turing Complete™️ but when you have to hide all the guns and knives in jdk.internal.misc.Unsafe something is clearly wrong.
  
  Nice ATM machine.

Doubles have a much higher max value than ints, so if the method were to convert all doubles to ints they would not work for double values above 2^31-1.
(It would work, but any value over 2^{31-1 passed to such a function would get clamped to 2}31-1)
- So why not return a long or whatever the 64 bit int equivalent is?
  
  To avoid a type conversion that might not be expected. Integer math in Java differs from floating point math.
  Math.floor(10.6) / Math.floor(4.6) = 2.5 (double)
  If floor returned a long, then
  Math.floor(10.6) / Math.floor(4.6) = 2 (long)
  If your entire code section is working with doubles, you might not like finding Math.floor() unexpectedly creating a condition for integer division and messing up your calculation. (Have fun debugging this if you're not actively aware of this behavior).
  
  Because even a long (64-bit int) is too small :)
  A long can hold 2^64-1 = 1.84E19
  A double can hold 1.79E308
  Double does some black magic with an exponent, and can hold absolutely massive numbers!
  Double also has some situations that it defines as "infinity", a concept that does not exist in long as far as I know (?)
- But there's really no point in flooring a double outside of the range where integers can be represented accurately, is there.
- what about using two ints
  
  What about two int64_t
  
  A BigDecimal?

Makes sense, how would you represent floor(1e42) or ceil(1e120) as integer? It would not fit into 32bit (unsigned) or 31bit (signed) integer. Not even into 64bit integer.
- BigInt (yeah, not native everywhere)
  
  I feel this is worse than double though because it's a library type rather than a basic type but I guess ceil and floor are also library functions unlike toInt

It would be kinda dumb to force everyone to keep casting back to a double, no? If the output were positive, should it have returned an unsigned integer as well?
- int coerces to double automatically, without explicit casting
  
  The CPU has to do real work to convert between float and int types. Returning an int type would just be giving the CPU extra work to do for no reason
- I think one of the main reason to use floor/ceilling is to predictably cast a double into int. This type signature kind of defeats this important purpose.
  I don't know this historical context of java, but possibly at that time, people see type more of a burden than a way to garentee correctness? (which is kind of still the case for many programmers, unfortunately.
  
  You wouldn’t need floor/ceil for that. Casting a double to an int is already predictable as the java language spec explicitly says how to do it, so any JVM will do this the exact same way.
  The floor/ceil functions are simply primitive math operations and they are meant to be used when doing floating point math.
  All math functions return the same type as their input parameters, which makes sense. The only exception are those that are explicitly meant for converting between types.

python is like this also. I don’t remember a language that returned ints
- Python 2 returns a float, Python 3 returns an int iirc.

My God this is the most relevant meme I've ever seen

AFAIK most typed languages have this behaviour.
- Because ints are way smaller. Over a certain value it would always fail.
  
  Yea but at those values floating points can't represent fractions anyway

Logic, in math, if you have a real and you round it, it's always a real not an integer. If we follow your mind with abs(-1) of an integer it should return a unsigned and that makes no sense.
- in math, if you have a real and you round it, it's always a real not an integer.
  No, that's made up. Outside of very specific niche contexts the concept of a number having a single well-defined type isn't relevant in math like it is in programming. The number 1 is almost always considered both an integer and a real number.
  If we follow your mind with abs(-1) of an integer it should return a unsigned and that makes no sense.
  How does that not make sense? abs is always a nonnegative integer value, why couldn't it be an unsigned int?
  
  I'm ok with that, but what I mean is that it makes no sense to change the type of the provided variable if in mathematics the type can be the same.

It's like Java not having unsigned integers...

Try Math.round. It’s been like ten years since I used Java, but I’m pretty sure it’s in there.

I like big numbers and I cannot tell a lie

the programming language Java meaning coffee is perfect because, like coffee, it tastes like shit but gets the job done
- I think you need to try some lighter-roasted, higher-quality beans which were roasted fairly recently and only grind them a day or so before you use them. There are also different brewing methods and coffee/water ratios that you can try.
  
  I love and consume lots of coffee but I sincerely believe it only tastes good because I associate the taste with the boost it gives. Exactly like cigarettes taste tolerable, good even, when you smoke them regularly.
- It is shit, Austin

77 comments