BigInteger bigIntFromDouble = new BigInteger(179032.6541);
Console.WriteLine(bigIntFromDouble);
BigInteger bigIntFromInt64 = new BigInteger(934157136952);
Console.WriteLine(bigIntFromInt64);

long longValue = 6315489358112;      
BigInteger assignedFromLong = longValue;
Console.WriteLine(assignedFromLong);

BigInteger assignedFromDouble = (BigInteger) 179032.6541;
Console.WriteLine(assignedFromDouble);   
BigInteger assignedFromDecimal = (BigInteger) 64312.65m;      
Console.WriteLine(assignedFromDecimal);

byte[] byteArray = { 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0};
BigInteger newBigInt = new BigInteger(byteArray);
Console.WriteLine("The value of newBigInt is {0} (or 0x{0:x}).", newBigInt);

string positiveString = "91389681247993671255432112000000";
string negativeString = "-90315837410896312071002088037140000";
BigInteger posBigInt = 0;
BigInteger negBigInt = 0;

try {
   posBigInt = BigInteger.Parse(positiveString);
   Console.WriteLine(posBigInt);
}
catch (FormatException)
{
   Console.WriteLine("Unable to convert the string '{0}' to a BigInteger value.", 
                     positiveString);
}

if (BigInteger.TryParse(negativeString, out negBigInt))
  Console.WriteLine(negBigInt);
else
   Console.WriteLine("Unable to convert the string '{0}' to a BigInteger value.", 
                      negativeString);

BigInteger number = BigInteger.Multiply(Int64.MaxValue, 3);
number++;
Console.WriteLine(number);

BigInteger number = Int64.MaxValue ^ 5;
int repetitions = 1000000;
// Perform some repetitive operation 1 million times.
for (int ctr = 0; ctr <= repetitions; ctr++)
{
   // Perform some operation. If it fails, exit the loop.
   if (! SomeOperationSucceeds()) break;
   // The following code executes if the operation succeeds.
   number++;
}

BigInteger number = Int64.MaxValue ^ 5;
int repetitions = 1000000;
int actualRepetitions = 0;
// Perform some repetitive operation 1 million times.
for (int ctr = 0; ctr <= repetitions; ctr++)
{
   // Perform some operation. If it fails, exit the loop.
   if (! SomeOperationSucceeds()) break;
   // The following code executes if the operation succeeds.
   actualRepetitions++;
}
number += actualRepetitions;

BigInteger number = BigInteger.Pow(Int64.MaxValue, 2);     
Console.WriteLine(number);

// Write the BigInteger value to a byte array.
byte[] bytes = number.ToByteArray();

// Display the byte array.
foreach (byte byteValue in bytes)
   Console.Write("0x{0:X2} ", byteValue);
Console.WriteLine();

// Restore the BigInteger value from a Byte array.
BigInteger newNumber = new BigInteger(bytes);
Console.WriteLine(newNumber);

short originalValue = 30000;
Console.WriteLine(originalValue);

// Convert the Int16 value to a byte array.
byte[] bytes = BitConverter.GetBytes(originalValue);

// Display the byte array.
foreach (byte byteValue in bytes)
   Console.Write("0x{0} ", byteValue.ToString("X2"));
Console.WriteLine();

// Pass byte array to the BigInteger constructor.
BigInteger number = new BigInteger(bytes);
Console.WriteLine(number);

int negativeNumber = -1000000;
uint positiveNumber = 4293967296;

byte[] negativeBytes = BitConverter.GetBytes(negativeNumber); 
BigInteger negativeBigInt = new BigInteger(negativeBytes);
Console.WriteLine(negativeBigInt.ToString("N0"));

byte[] tempPosBytes = BitConverter.GetBytes(positiveNumber);
byte[] positiveBytes = new byte[tempPosBytes.Length + 1];
Array.Copy(tempPosBytes, positiveBytes, tempPosBytes.Length);
BigInteger positiveBigInt = new BigInteger(positiveBytes);
Console.WriteLine(positiveBigInt.ToString("N0"));

BigInteger positiveValue = 15777216;
BigInteger negativeValue  = -1000000;

Console.WriteLine("Positive value: " + positiveValue.ToString("N0"));
byte[] bytes = positiveValue.ToByteArray();

foreach (byte byteValue in bytes)
   Console.Write("{0:X2} ", byteValue);
Console.WriteLine();
positiveValue = new BigInteger(bytes);
Console.WriteLine("Restored positive value: " + positiveValue.ToString("N0"));

Console.WriteLine();
   
Console.WriteLine("Negative value: " + negativeValue.ToString("N0"));
bytes = negativeValue.ToByteArray();
foreach (byte byteValue in bytes)
   Console.Write("{0:X2} ", byteValue);
Console.WriteLine();
negativeValue = new BigInteger(bytes);
Console.WriteLine("Restored negative value: " + negativeValue.ToString("N0"));

BigInteger negativeNumber = -1000000;
BigInteger positiveNumber  = 15777216;

string negativeHex = negativeNumber.ToString("X");
string positiveHex = positiveNumber.ToString("X");

BigInteger negativeNumber2, positiveNumber2;  
negativeNumber2 = BigInteger.Parse(negativeHex, 
                                   NumberStyles.HexNumber);
positiveNumber2 = BigInteger.Parse(positiveHex,
                                   NumberStyles.HexNumber);

Console.WriteLine("Converted {0:N0} to {1} back to {2:N0}.", 
                   negativeNumber, negativeHex, negativeNumber2);                                         
Console.WriteLine("Converted {0:N0} to {1} back to {2:N0}.", 
                   positiveNumber, positiveHex, positiveNumber2);

//引入命名空间
using System;
using System.Globalization;
using System.Numerics;

public struct HexValue
{
   public int Sign;
   public string Value;
}

public class Example
{
   public static void Main()
   {
      uint positiveNumber = 4039543321;
      int negativeNumber = -255423975;

      // Convert the numbers to hex strings.
      HexValue hexValue1, hexValue2;
      hexValue1.Value = positiveNumber.ToString("X");
      hexValue1.Sign = Math.Sign(positiveNumber);
      
      hexValue2.Value = Convert.ToString(negativeNumber, 16);
      hexValue2.Sign = Math.Sign(negativeNumber);
      
      // Round-trip the hexadecimal values to BigInteger values.
      string hexString;
      BigInteger positiveBigInt, negativeBigInt;
      
      hexString = (hexValue1.Sign == 1 ? "0" : "") + hexValue1.Value;
      positiveBigInt = BigInteger.Parse(hexString, NumberStyles.HexNumber);      
      Console.WriteLine("Converted {0} to {1} and back to {2}.", 
                        positiveNumber, hexValue1.Value, positiveBigInt);

      hexString = (hexValue2.Sign == 1 ? "0" : "") + hexValue2.Value;
      negativeBigInt = BigInteger.Parse(hexString, NumberStyles.HexNumber);      
      Console.WriteLine("Converted {0} to {1} and back to {2}.", 
                        negativeNumber, hexValue2.Value, negativeBigInt);
   }
}