Page 152 - CSharp/C#

Chapter 18: BigInteger

Remarks

When To Use

BigInteger objects are by their very nature very heavy on RAM. Consequently, they should only be
used when absolutely necessary, ie for numbers on a truly astronomical scale.

Further to this, all arithmetic operations on these objects are an order of magnitude slower than
their primitive counterparts, this problem gets further compounded as the number grows as they
are not of a fixed size. It is therefore feasibly possible for a rogue BigInteger to cause a crash by
consuming all of the available RAM.

Alternatives

If speed is imperative to your solution it may be more efficient to implement this functionality
yourself using a class wrapping a Byte[] and overloading the necessary operators yourself.
However, this does require a significant amount of extra effort.

Examples

Calculate the First 1,000-Digit Fibonacci Number

Include using System.Numerics and add a reference to System.Numerics to the project.

using System;
using System.Numerics;

namespace Euler_25
{
class Program
{
static void Main(string[] args)
{
BigInteger l1 = 1;
BigInteger l2 = 1;
BigInteger current = l1 + l2;
while (current.ToString().Length < 1000)
{
l2 = l1;
l1 = current;
current = l1 + l2;
}
Console.WriteLine(current);
}
}
}

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