帮我看看这个奇怪的问题，困扰了我很久！
为何我单步运行的时候每次出现的数字不一样，一旦用for循环输出的数字都是一样的了，包括用数组输出的时候也是一样的结果，请大家帮助！
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using rocktest;
using System.Collections;
namespace rocktest
{
class programm
{
public static int PoissonRandomNumber(double Lemda)
{
double u;
int Z = 0;
double L;
double p = 1.0;
L = Math.Exp(-Lemda);
Random rand = new Random();

do
{
Z = Z + 1;
u = rand.NextDouble();
p = p * u;

}
while (p >= L);
return Z - 1;
}
static void Main(string[] args)
{
//for (int i = 0; i < 10; i++)
Console.WriteLine(rocktest.Program.BinomialRandom(0.5, 10));

}
}
}

[解决办法]
楼主怎么还没明白呢？：（

C# code

using System; using System.Collections.Generic; using System.Linq; using System.Text; using rocktest; using System.Collections; namespace rocktest {   class programm {   static Random rand = new Random();  public static int PoissonRandomNumber(double Lemda)         {             double u;             int Z = 0;             double L;             double p = 1.0;             L = Math.Exp(-Lemda);             do             {                 Z = Z + 1;                 u = rand.NextDouble();                 p = p * u;             }             while (p >= L);             return Z - 1;         }           static void Main(string[] args)           {                 //for (int i = 0; i < 10; i++)             Console.WriteLine(rocktest.Program.BinomialRandom(0.5, 10));             } } }