Thread: Huge Numbers in C++

Hi guys...
I'm pretty new to C++. I'm working with Visual C++ 6.0 on Windows XP, doing mainly console apps at the moment.

My question deals with how C++ handles large numbers--like > 5,000,000,000. As I understand it, the biggest number that an int variable can handle is 2,147,483,647, and the biggest than an unsigned int can handle is 4,294,967,295. That ok for most programs... but I can't imagine that no C++ application is able to handle bigger numbers!

Any solutions are welcome--either accepted methods or rough hacks. Is there maybe a header file that I can include that will give me additional data types? Like I said I'm pretty new to this (although I'm familiar with many web-based languages, like JavaScript, PHP, and ASP, so I know the principles of OOP programming). Any help you can provide is extremely welcome... but please treat me like the dumbest programmer you've ever met! All the details are important to me. Thanks!

By the way, here's the program I'm working on. The goal is to figure out the probabity of 2 out of 100 people in a room sharing the same birthday. Right now, I'm trying to find the probability of the two people not sharing the same day, and the program is coded to generate the numerator:

Code:

#include <iostream>
using namespace std;

int main(void)
{
	int numDays = 365;
	int numPeople = 100;
	unsigned int product = 1;
	for (int i = 0; i < numPeople; i++)
	{
		product = product * (numDays - i);
		cout << product << "\n";
	}

	return 0;
}

Thanks again!

Here are some threads you can read:
http://cboard.cprogramming.com/search.php?searchid=5250

Code:

#include <iostream>

int main(void)
{
  unsigned long long int x= (unsigned long long)-1;
  cout<<"Size:  "<< sizeof x<<endl;
  cout<<"Value: "<< x <<endl;
  return 0;
}

Output:

Size: 8
Value: 18446744073709551615

Damn, I just realized my link is no longer valid....

It was a search on "GMP".

gg

Thantos your code gave me an error about long followed by long is illegal. I found that this though would give the same ouput:

Code:

#include <iostream>

int main()
{
	unsigned __int64 x = (unsigned __int64)-1;
	std::cout << x << std::endl;
}

__int64 is MSVC specific....

change "unsigned long long int" to "unsigned long long"

gg

Try the following:

cout<<sizeof (long);

If it is 8 then use unsigned long instead of long long.

Originally Posted by Codeplug

change "unsigned long long int" to "unsigned long long"

My bad....

"long long int" is C99 and is suppored in C89 mode by GCC as a compiler extension.

Here's the scoop:
http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html

gg

i also need to use big numbers in an encryption program i am working on.
but i need numbers about 1 * 10^1000
how do i get numbers so big?
i downloaded that gmp, but i get lots of errors