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Closed 14 years ago.
How can I add very large numbers in C++?
consider a "bignum" library like: http://gmplib.org/ or http://ttmath.slimaczek.pl/ttmath. take a look at a simple bignum class: http://www.circlemud.org/~jelson/560/
Do a Google on "Bigint C++" This will provide you with a list of arbitrator precision integer arithmetic libraries.
You can find a big decimal implementation at http://speleotrove.com/decimal/
How big is "very large"? A signed long int can go up to 2,147,483,647 and an unsigned long int can go up to 4,294,967,295.
GMP has a GMPXX C++ wrapper which is kind of nice. GMP supports both integer and floating point numbers, and is LGPL'ed.
I've used it. It's ok, but watch out for creating lots of temporaries. (Potential efficiency hit.)
You could use a library like LiDIA for a 'big integer' class.
Related
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What variable type for extremely big integer numbers?
(1 answer)
Closed 6 years ago.
"unsigned long int" keeps becoming 0. It has to be a really big integer that I can operate multiplication and modulo on.
Example: 1234^123 % 1234
If you're using gcc you can try __uint128_t or maybe use double instead unless you need to do bitwise operations
Two roads you got
1. Implement what you need by learning how to do large calculations using integer arrays with maths tricks for speed up OR
2. Use a library
I would suggest to go with 2nd option if you are not tied to use external library. One such bigNum library is ttmath
OR
If you have a option to switch to java, then java has builtin BigInteger, BigDecimal and more functionalities supported. Look at BigInteger javadoc
This question already has an answer here:
What variable type for extremely big integer numbers?
(1 answer)
Closed 7 years ago.
How can i implement "Big-Integer" for c/c++ programming? Is there any build function in c/c++ library? or do I have to implement the Function for it?
{
BigInt fac=1;
int value=25;
for(int i=1;i<=25;i++){
fac=fac*i;
}
cout<<fac<<endl;
}
I am trying like this but seems like there is no data type like "Big Int" .
You can use boost::multiprecision::cpp_int if you need an arbitrary precision integer. If you need it to be fast, you can use boost::multiprecision with linking to one of several options of an external back-end.
Using a array to store the single integers at a time will help you achieving the desired effect!
This is the one of the best tutorial from codechef for this well known big-int problems!
Hope that helps!
For example, how can I use the result of 1000^1000 for arithmetic? I don't think there's a library that can accommodate that, all I see at most is 100 number digits.
Use an arbitrary-precision arithmetic library like GMP or Boost.Multiprecision.
What you are looking for is a library like GMP or Boost-Multiprecision or TTmath.
Or, you might challenge yourself to write a low level representation that handles longer than standard bit representations, and do arithmetic with it.
Stick with the first option though, if it does the job you have in mind.
i have a float value that is hundreds of digits long (like the first 100 digits of pi - 3) and need a way to operate on it. is there any way to store and operate on the float that has a large number of decimals and maintain much precision with built in libraries? is there anything like python's Decimal module in c++?
The other answers all point to high precision integer libraries. There are however a few floating point libraries around:
The High Precision Arithmetic library
The GNU Multiple Precision Arithmetic Library (GMP) "Arithmetic without limitations"
The GNU multiple-precision floating-point computations with correct rounding (the GNU MPFR library). There's also a C++ wrapper.
NTL: A Library for doing Number Theory. Together with NTL::RR you can use this even within boost.
The LBNL double-double precision, quad-double precision and arbitrary precision software.
... and don't forget the possibility that you can always implement your own solution. (Might not be the most effective or fastest solution, but it's "the" solution if you want to learn something.
No built-in library, but you can do that using Bignum arithmetics :) http://en.wikipedia.org/wiki/Arbitrary-precision_arithmetic.
What a Bignum is: an array (vector) of digits. You can easily implement sum/difference....
I've actually asked something simillar here: STL big int class implementation
Unless it is some extra exotic platform, where a float is 100+ bytes long, you will find it hard to archive what you want without a library for big numbers.
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Closed 12 years ago.
Possible Duplicate:
Should I use double or float ?
When would I rather use double and when should I use float?
It's all about precision.
If you need to store very precise numbers then use a double.
If you need to store less precise numbers and are worried about the size of memory you're using then use a float.
The only time you need to use float is when you are storing large arrays of numbers. There is generally little difference in speed between the two and natively most things are double anyway.
Use double when you require the range it supports. Refer to Range of floating-point numbers. You should also typically use the native type, so if you're doing graphics or GPU programming, probably better stick to floats.
But whatever you do, please, do not use either to represent currency or money.