我靠着都不会呀！！！ 给你一个吧。 using System; using System.Collections ;

class Ping { static void Main() { decimal P=0.00M; decimal M =0.00M; System.Random r=new Random (); ArrayList A=new ArrayList ();

Console.WriteLine ("please input a number:"); decimal a=decimal.Parse (Console.ReadLine ());

for(int i=1;i<=a;i++) { A.Add (r.Next (0,100)); }

// 察看A中的元素 for(int i=0;i<A.Count ;i++) { decimal N=0.00M; Console.WriteLine (A[i].ToString ()); //ArrayList的数据转换 N=decimal.Parse (A[i].ToString ());

// 求这几个数的和 M+= N; } // 求平均数 P=M/a;

Console.WriteLine ("这"+a+"个数的平均数为:"+P);

} }

using System; using System.Collections; class Sum_Average { public static void Main() { int sum=0; float average=0.0f; Random r=new Random (); ArrayList myArrayList=new ArrayList (); Console.WriteLine ("你想算几个数的和,并求它的平均值:"); int iMax=int.Parse (Console.ReadLine ()); for(int i=0;i<iMax;i++) { myArrayList.Add (r.Next (0,100)); } Console.WriteLine ("这{0}个数是:",iMax); foreach(int pins in myArrayList) { Console.WriteLine (pins); } for(int j=0;j<iMax;j++) { sum+=(int)myArrayList[j]; } Console.WriteLine ("这{0}个数的和是:{1}",iMax,sum); average = (float)sum / iMax; Console.WriteLine ("这{0}个数的平均值是:{1}",iMax,average);

} } using System; public class book_ticket { public static void Main() { int[] A=new int[10]; int next; Console.WriteLine ("欢迎使用南方航空公司预订票系统:"); Console.WriteLine ("1预订头等仓:"); Console.WriteLine ("2预订经济仓:"); Console.WriteLine ("-1退出:"); do { Console.WriteLine ("请选择:"); next=int.Parse (Console.ReadLine ()); switch(next) { case 1: Console.WriteLine ("请输入座位号:(1-5)"); int next1=int.Parse (Console.ReadLine ()); if(A[next1-1]==1) Console.WriteLine ("抱歉...该座位{0}已被订.",next1); else A[next1-1]=1; Console.WriteLine ("座位{0}预订成功.欢迎下次再来!",next1); break; case 2: Console.WriteLine ("请输入座位号:(6-10)"); int next2=int.Parse (Console.ReadLine ()); if(A[next2-1]==1) Console.WriteLine ("抱歉...该座位{0}已被订.",next2); else A[next2-1]=1; Console.WriteLine ("座位{0}预订成功.欢迎下次再来!",next2); break; case -1: break; default: return; } }while(next!=-1);

} }