BigInteger Structure

Where do you turn to if you have an integer to that is to large for the primitives supplied by the .NET Framework? The BigInteger Structure! The BigInteger Structure in the System.Numerics namespace allows for any size signed integer to be represented.

Unlike the built in primitives such as int, byte, or long, the BigInteger structure does not have a lower or upper limit as represented through the MinValue and MaxValue properties on the primitives.

Like primitives, BigInteger is immutable but this comes with a caveat… You can get an OutOfMemoryException if you perform operations on the value that causes it to grow to large.

BigInteger has overloaded the standard mathematical operators so that you can do math just like any other primitive numeric type:

var x = new BigInteger(1);
var y = new BigInteger(200);

var z = x + y;

Assert.AreEqual(201, z);

Creating a number larger than any of the primitive types can be achieved in several ways:

// Using a byte array
var bytes = new byte[] {1, 2, 34, 45, 12, 54, 23, 42, 88, 45, 45, 45, 12};
var x = new BigInteger(bytes);

// Math on  a large number
var x = BigInteger.Multiply(Int32.MaxValue, 99999);

// Parsing a string
string googol = "1".PadRight(100, '0');
var x = BigInteger.Parse(googol);

More Information

You find out more about the BigInteger structure on the BigInteger MSDN page. Becuase the number is large and immutable, there is information on that page that tells you how to best handle performance problems you might run into.

This type will be available in the cross platform .NET Core Library.