Random伪随机数

Random伪随机数

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;

namespace 伪随机数
{
    class Program
    {
        static void Main(string[] args)
        { 
            Random rnd=new Random (); 
            char c;
            Random ro = new Random();
            Console.WriteLine("{0}", ro);


            int d = ro.Next();
            Console.WriteLine("{0}",d);

            Random rc = new Random();
            int f = rc.Next();
            Console.WriteLine("{0}",f);

            //Thread.Sleep(10000);
            //Console.WriteLine("time later 10000");


            Random s = new Random();
            double cc = s.NextDouble();
            Console.WriteLine("{0}",cc);


            int count = 4;
            Random[] rnds = new Random[count];
            int[] ss = new int[4];
            for (int i = 0; i < count; i++)
            {
                rnds[i] = new Random(unchecked((int)(DateTime.Now.Ticks >> i)));
                ss[i] = rnds[i].Next();
                Console.WriteLine("{0}",ss[i]);
            }

            Random ww = new Random();
            double ee = ww.NextDouble();
            string gg = string.Format("{0:F5}", ee);
            Console.WriteLine("{0}",gg);

            int k = rc.Next(65, 91);
            c = (char)k;
            Console.WriteLine("{0}", c);

            string rr;
            rr = GetLetter(rnd);
            Console.WriteLine("{0}",rr);
            Console.ReadKey();
         
         } 
        public static  string GetLetter(Random rnd)
         {
                // A-Z  ASCII值  65-90
                // a-z  ASCII值  97-122
                
                 int i = rnd.Next(65, 123);
                 char o = (char)i;
                 if (char.IsLetter(o))
                 {
                    return o.ToString();
                  }
                 else
                 {
                     // 递归调用，直到随机到字母
                      return GetLetter(rnd);
                  }
            }
    }
}

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