C#实现大数字的运算

1、添加引用：System.Numerics.dll

2、添加命名空间：using System.Numerics;

3、实例：

3.1判断一个数字是不是质数

复制代码 代码如下:

static void Main(string[] args)

{

Console.WriteLine("请输入一个很大的数字：");

string bigNumber = Console.ReadLine();

BigInteger bigInteger = BigInteger.Parse(bigNumber);

bool isNumber=false;

for (BigInteger i = 2; i < BigInteger.Pow(bigInteger, 2);i++ )

{

if (bigInteger % i == 0)

{

isNumber = true;

break;

}

}

if (isNumber)

{

Console.WriteLine("不是质数");

}

else

{

Console.WriteLine("是质数");

}

Console.ReadLine();

}

3.2实现两个大数的加减乘除

复制代码 代码如下:

static void Main(string[] args)

{

Console.Write("请输入第一个大数字:");

string bigNum1 = Console.ReadLine();

BigInteger bigInt1 = BigInteger.Parse(bigNum1);

Console.Write("请输入第二个大数字:");

string bigNum2 = Console.ReadLine();

BigInteger bigInt2 = BigInteger.Parse(bigNum2);

Console.Write(Environment.NewLine);

BigInteger addNum = bigInt1 + bigInt2;

BigInteger subNum = bigInt1 - bigInt2;

BigInteger purNum = bigInt1 * bigInt2;

BigInteger divNum = bigInt1 / bigInt2;

Console.WriteLine("两大数相加结果为：{0}",addNum);

Console.WriteLine("两大数相减结果为：{0}",subNum);

Console.WriteLine("两大数相乘结果为：{0}",purNum);

Console.WriteLine("两大数相除结果为：{0}",divNum);

Console.ReadLine();

}