Int64：该结构用于表示 64 位有符号整数。Int64 可以存储两种类型的值，包括负值和正值，范围在 -9,223,372,036,854,775,808 到 +9、223,372,036,854,775,807 之间

例子：

// C# program to show the
// difference between Int64
// and UInt64

using System;
using System.Text;

public
class GeekdocsDemo {

// Main Method
static void Main(string[] args) {

    // printing minimum & maximum values
    Console.WriteLine("Minimum value of Int64: " + Int64.MinValue);
    Console.WriteLine("Maximum value of Int64: " + Int64.MaxValue);
    Console.WriteLine();

    // Int64 array
    Int64[] arr1 = {-3, 0, 1, 3, 7};

    foreach (Int64 i in arr1)
    {
    Console.WriteLine(i);
    }
}
}

运行结果：

Minimum value of Int64: -9223372036854775808
Maximum value of Int64: 9223372036854775807

-3
0
1
3
7

UInt64： UInt64结构用于表示 64 位无符号整数。UInt64 只能存储范围从 0 到 18,446,744,073,709,551,615 的正值。

例子：

// C# program to show the
// difference between Int64
// and UInt64

using System;
using System.Text;

public class GeekdocsDemo{

    // Main Method
    static void Main(string[] args)
    {

        //printing minimum & maximum values
        Console.WriteLine("Minimum value of UInt64: " + UInt64.MinValue);
        Console.WriteLine("Maximum value of UInt64: " + UInt64.MaxValue);
        Console.WriteLine();

        //Int64 array
        UInt64[] arr1 = { 13, 0, 1, 3, 7};

        foreach (UInt64 i in arr1)
        {
            Console.WriteLine(i);
        }
    }
}

运行结果：

Minimum value of UInt64: 0
Maximum value of UInt64: 18446744073709551615

13
0
1
3
7

C#中Int64和UInt64的区别