[C++] how do i get really long numbers
 

this is in c++ im trying to get really long numbers, say 20 digits or 15 something like that.

once i figure that part out ill probably have more questions but thats all for now


thanks

You could write your own class and overload the operators...

internally store the numbers as an array (or std::vector, ...)

but I think there will be allready pre-written classes on the net for doing calculations with bignumbers

What compiler? Many compilers have a 64 bit integer built-in. That will handle up to 15 to 18 digit numbers.

To go beyond this, you normally have to find or write your own code, or you can use doubles.

Doubles can approximate really large numbers, but they don't remember every digit of them. I doubt they will be useful, but depending on your purposes...

Writing your own isn't all that hard, especially if you don't need to divide them by each other, or multiply them together.

Again depending on what you need them for, there are a bunch of options. Coding your own isn't too bad, but any sort of division algorithms can get nasty in a hurry. If are doing something like does include a lot of mathmatical tinkering, an RSA implementation for example, you might want to look around for some open source packages.

MAPM is a c package MAPM that's pretty damned nice, you might want to give it a shot, there is a C++ wrapper class for it as well if I remember correctly...

grr too complicated... i wrote the program in javascript and it worked so im finished thanks for the help tho, if i decide to write it in c++ ill come back to these options... thanks

Use Lisp
 

You could have used Lisp, most implementations of Common Lisp guarantee that x+1 > x in all cases. So no matter how big the number, it will always work. The good news about this big number implementation is that since it is builtin, you don't have to do anything differently to use it, and it is a well-built well-supported implementation that typically is quite quick.

Remember Greenspun's tenth rule of programming:

*nod*, many languages have built-in arbitrary precision integers and doubles. perl for example.

you could always half ass it with an array and then make your own math sub routeins.

but there is a better way.

You guyz are making it too complicated!!! :D


This makes it all better though.....



int main()
{
return 0;
}

MSVC 6.0 or greater has LONGLONG or ULONGLONG which are 64 bit ints

microsoft compilers have 64 bit ints as type _int64