C#的foreach循环替换for循环

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

namespace Test1111
{
    class Program
    {
        static void Main(string[] args)
        {
            ArrayList studentList = new ArrayList();
            studentList.Add("a");
            studentList.Add("b");
            studentList.Add("c");
            studentList.Add("d");
            studentList.Add("e");
            studentList.AddRange(new int[]{6,7,8,9});
            studentList.Add("ssss");
            Console.WriteLine("集合元素为：");
            //for (int i = 0; i<studentList.Count;i++ )
            //{
            //    Console.Write(studentList[i]);
            //}

            foreach (object x in studentList)
            {
                Console.Write("{0} ", x);
            }

            Console.WriteLine();


            studentList.Remove("e");
            studentList.RemoveAt(1);
            studentList.RemoveRange(4,2);
            Console.WriteLine("集合元素为：");
            //for (int i = 0; i < studentList.Count; i++)
            //{
            //    Console.Write(studentList[i]);
            //}


            foreach (object x in studentList)
            {
                Console.Write("{0} ", x);
            }
            Console.WriteLine();


            studentList.Insert(1,"fff");
            studentList.InsertRange(0,new string[]{"张三","李四"});
            Console.WriteLine("集合元素为：");
            //for (int i = 0; i < studentList.Count; i++)
            //{
            //    Console.Write(studentList[i]);
            //}
            foreach (object x in studentList)
            {
                Console.Write("{0} ", x);
            }
            Console.WriteLine();

            studentList.Add("王五");
            if (!studentList.Contains("王五"))
            {
                studentList.Add("王五");
            }
            else {
                Console.WriteLine("集合中已经有王五了！");
            }

            //for (int i = 0; i<studentList.Count;i++ )
            //{
            //    Console.Write(studentList[i]);
            //}

            foreach (object x in studentList)
            {
                Console.Write("{0} ", x);
            }


            Console.ReadLine();
        }
    }
}