I have looked everywhere but I couldnt find any information related to this topic.
Also, Is there a java - like Long / BigDecimal datatype in dart?
That depends if you are running in the Dart VM or compiling to JavaScript.
On the Dart VM an int is arbitrary precision and has no limit.
When compiling to JavaScript you are actually using floating point numbers, since that is all that JavaScript supports. This means you are restricted to representing integers within the range -253 to 253
Dart 2
For dart2js generated JavaScript Pixel Elephants answer is still true.
within the range -253 to 253
Other execution platforms have fixed-size integers with 64 bits.
The type BigInt was added to typed_data
Since Dart 2.0 will switch to fixed-size integers, we also added a BigInt class to the typed_data library. Developers targeting dart2js can use this class as well. The BigInt class is not implementing num, and is completely independent of the num hierarchy.
Dart 1
There are also the packages
- https://pub.dartlang.org/packages/bignum
- https://pub.dartlang.org/packages/decimal
I prefer this one:
int hugeInteger = double.maxFinite.toInt()
Related
In java we can just Integer.maxValue but dart there is not this method.
I am using int max = 1<<32 but this doesn't work properly when compiling to javascript.
What is the best way to get the integer maximum value using dart language?
I was using dart_numerics package in my app for another reason and found it while typing
There is no method because the int maximum values are fixed.
According to the documentation:
Integers While the language specifies an arbitrarily sized integer,
for performance reasons the VM has three different internal integer
representations: smi (rhymes with pie), mint, and bigint. Each
representation is used to hold different ranges of integer numbers
(see the table). The VM automatically switches between these
representations behind the scenes as numbers grow and shrink in range.
You can read about that here: https://dart.dev/articles/archive/numeric-computation
This is a description of the dart documentation
But
void main() {
print(3 >>> 1);
}
Unable to compile, got an error
Error: Expected an identifier, but got '>'.
The documentation is ahead of its time.
I assume the table comes from https://www.dartlang.org/guides/language/language-tour#operators
Dart removed the >>> operator in 2012 when it changed its integer type to arbitrary precision integers (except when compiled to JavaScript). There is no longer a >>> operator in Dart, and there haven't been for several years.
In Dart 2.0, Dart changed its integer type to 64-bit integers (still except when compiled to JavaScript). We plan to reintroduce the >>> operator, and have added it to the language specification, we it has not been implemented by all platforms yet, so it is not available.
The document here was just a little too optimistic about when we release that operator. It won't be in Dart 2.3, as was initially planned.
For all I know a signpropagating right shift operator in Dart is a >> b and not >>>. I don't think >>> exists. Either your source is incorrect or they have a mistake in their docs.
I run Lua on a CPU without dedicated floating point HW, depending on SW emulation.
From luaopt.h I can see that some macros are set to double, but it does not clearly state when floats are used and its a little hard to track it.
If my script does simple stuff like:
a=0
a=a+1
for...
Would that involve a floating point operations at any level?
If no that's fine, but what is then the benefit to change macros to long?
(I tried of course but did not work....)
All numeric operations in Lua are performed (according to the default configuration) in floating point. There is no distinction made between floating point and integer, all values are simply numbers.
The actual C type used to store a Lua number is set in luaconf.h, and it is both allowed and even practical to change that to a suitable integral type. You start by changing LUA_NUMBER from double to int, long, or perhaps ptrdiff_t. Then you will find you need to tweak the related macros that control the conversions between strings and numbers. And, of course, you will likely need to eliminate most or all of the base math library since math.sin() and its friends and neighbors are not particularly useful over integers.
The result will be a Lua interpreter where all numbers are integers. The language will still allow you to type 3.14, but it will be stored as 3. Your code will likely not be completely portable to a Lua interpreter built with the standard configuration since a huge amount of Lua code casually assumes that floating point arithmetic is permitted, and remember that your compiled byte code will definitely not be compatible since byte code will store numbers as LUA_NUMBER.
There is LNUM patch (used, for example, by OpenWrt project which relies heavily on Lua for providing Web UI on hardware without FPU) that allows dual integer/floating point representation of numbers in Lua with conversions happening behind the scenes when required. With it most integer computations will be performed without resorting to FPU. Unfortunately, it's only applicable to Lua 5.1; 5.2 is not supported.
How could I handle operations with a number like:
48534588306961133067968196965257961415756656521818848750723547477673457670019632882524164647651492025728980571833579341743988603191694784406703
Nothing that I've tried worked so far... unsigned long, long long, etc...
What you need is a library that provides support for operations on integers of arbitrary length. However, from what I've been able to find out, there are no such libraries written in Objective-C.
You are nevertheless in luck as Objective-C is a superset of C. That makes it possible for you to use C libraries such as those described in the answers to this somewhat dated SO question.
Also, since the Clang compiler supports C++ and combining Objective-C and C++ code, you can probably use something like big int.
Note that none of the built-in types is even close to being big enough to represent numbers with as many digits as your examples. The biggest available integer type is unsigned long long, if you don't need negative numbers, and its size is 8 bytes/64 bits, which gives you a range of 0-18446744073709551615, or 20 digits max.
You could use JKBigInteger instead, it is a Objective-C wrapper around LibTomMath C library. And really easy to use and understand.
In your case:
JKBigInteger *int = [[JKBigInteger alloc] initWithString:#"48534588306961133067968196965257961415756656521818848750723547477673457670019632882524164647651492025728980571833579341743988603191694784406703"];
You can try here : http://gmplib.org/
GMP is a free library for arbitrary precision arithmetic, operating on signed integers, rational numbers, and floating point numbers. There is no practical limit to the precision except the ones implied by the available memory in the machine GMP runs on. GMP has a rich set of functions, and the functions have a regular interface.
As 64 bits support is not expected in the next version it is no longer an option to wait for the possibility to migrate our existing code base to unicode and 64-bit in one go.
However it would be nice if we could already prepare our code for 64-bit when doing our unicode translation. This will minimize impact in the event it will finally appear in version 2020.
Any suggestions how to approach this without introducing to much clutter if it doesn't arrive until 2020?
There's another similar question, but I'll repeat my reply here too, to make sure as many people see this info:
First up, a disclaimer: although I work for Embarcadero. I can't speak for my employer. What I'm about to write is based on my own opinion of how a hypothetical 64-bit Delphi should work, but there may or may not be competing opinions and other foreseen or unforeseen incompatibilities and events that cause alternative design decisions to be made.
That said:
There are two integer types, NativeInt and NativeUInt, whose size will
float between 32-bit and 64-bit depending on platform. They've been
around for quite a few releases. No other integer types will change size
depending on bitness of the target.
Make sure that any place that relies on casting a pointer value to an
integer or vice versa is using NativeInt or NativeUInt for the integer
type. TComponent.Tag should be NativeInt in later versions of Delphi.
I'd suggest don't use NativeInt or NativeUInt for non-pointer-based values. Try to keep your code semantically the same between 32-bit and 64-bit. If you need 32 bits of range, use Integer; if you need 64 bits, use Int64. That way your code should run the same on both bitnesses. Only if you're casting to and from a Pointer value of some kind, such as a reference or a THandle, should you use NativeInt.
Pointer-like things should follow similar rules to pointers: object
references (obviously), but also things like HWND, THandle, etc.
Don't rely on internal details of strings and dynamic arrays, like
their header data.
Our general policy on API changes for 64-bit should be to keep the
same API between 32-bit and 64-bit where possible, even if it means that
the 64-bit API does not necessarily take advantage of the machine. For
example, TList will probably only handle MaxInt div SizeOf(Pointer)
elements, in order to keep Count, indexes etc. as Integer. Because the
Integer type won't float (i.e. change size depending on bitness), we
don't want to have ripple effects on customer code: any indexes that
round-tripped through an Integer-typed variable, or for-loop index,
would be truncated and potentially cause subtle bugs.
Where APIs are extended for 64-bit, they will most likely be done with
an extra function / method / property to access the extra data, and this
API will also be supported in 32-bit. For example, the Length() standard
routine will probably return values of type Integer for arguments of
type string or dynamic array; if one wants to deal with very large
dynamic arrays, there may be a LongLength() routine as well, whose
implementation in 32-bit is the same as Length(). Length() would throw
an exception in 64-bit if applied to a dynamic array with more than 232
elements.
Related to this, there will probably be improved error checking for
narrowing operations in the language, especially narrowing 64-bit values
to 32-bit locations. This would hit the usability of assigning the
return value of Length to locations of type Integer if Length(),
returned Int64. On the other hand, specifically for compiler-magic
functions like Length(), there may be some advantage of the magic taken,
to e.g. switch the return type based on context. But advantage can't be
similarly taken in non-magic APIs.
Dynamic arrays will probably support 64-bit indexing. Note that Java
arrays are limited to 32-bit indexing, even on 64-bit platforms.
Strings probably will be limited to 32-bit indexing. We have a hard
time coming up with realistic reasons for people wanting 4GB+ strings
that really are strings, and not just managed blobs of data, for which
dynamic arrays may serve just as well.
Perhaps a built-in assembler, but with restrictions, like not being able to freely mix with Delphi code; there are also rules around exceptions and stack frame layout that need to be followed on x64.
First, look at the places where you interact with non-delphi libraries and api-calls,
they might differ. On Win32, libraries with the stdcall calling convenstion are named like _SomeFunction#4 (#4 indicating the size of the parameters, etc). On Win64, there is only one calling convention, and the functions in a dll are no more decorated. If you import functions from dll files, you might need to adjust them.
Keep in mind, in a 64 bit exe you cannot load a 32-bit dll, so, if you depend on 3rd party dll files, you should check for a 64-bit version of those files as well.
Also, look at Integers, if you depend on their max value, for example when you let them overflow and wait for the moment that happens, it will cause trouble if the size of an integer is changed.
Also, when working with streams, and you want to serialize different data, with includes an integer, it will cause trouble, since the size of the integer changed, and your stream will be out of sync.
So, on places where you depend on the size of an integer or pointer, you will need to make adjustments. When serializing sush data, you need to keep in mind this size issue as well, as it might cause data incompatibilities between 32 and 64 bit versions.
Also, the FreePascal compiler with the Lazarus IDE already supports 64-bit. This alternative Object Pascal compiler is not 100% compatible with the Borland/Codegear/Embarcadero dialect of Pascal, so just recompiling with it for 64-bit might not be that simple, but it might help point out problems with 64-bit.
The conversion to 64bit should not be very painful. Start with being intentional about the size of an integer where it matters. Don't use "integer" instead use Int32 for integers sized at 32bits, and Int64 for integers sized at 64bits. In the last bit conversion the definition of Integer went from Int16 to Int32, so your playing it safe by specifying the exact bit depth.
If you have any inline assembly, create a pascal equivalent and create some unit tests to insure that they operate the same way. Perform some timing tests of both and see if the assembly still runs faster enough to keep. If it does, then you will want to make changes to both as they are needed.
Use NativeInt for integers that can contain casted pointers.