字符串的练习

using System;
using System.IO;
using System.Text;
namespace _058_字符串的练习
{
    class Program
    {
        static void Main(string[] args)
        {
            //1、"abcdefg"->"gfedcba"
            string s = "abcdefg";
            char[] chs = s.ToCharArray();
            for (int i = 0; i < chs.Length / 2; i++)
            {
                char temp = chs[i];
                chs[i] = chs[chs.Length - i - 1];
                chs[chs.Length - i - 1] = temp;
            }
            s = new string(chs);
            Console.WriteLine(s);
            //2、"Hello C Sharp"->"Sharp C Hellp"
            string s1 = "Hello C Sharp";
            string[] str = s1.Split(" ", StringSplitOptions.RemoveEmptyEntries);
            for (int i = 2; i >=0 ; i--)
            {
                Console.Write(str[i]+" ");
            }
            Console.WriteLine();
            //s1 = string.Join(" ", s1);
            //3、从Email中提取用户名和域名：abc@163.com
            string email = "abc@163.com";
            string[] str1 = email.Split("@", StringSplitOptions.RemoveEmptyEntries);
            string userName = str1[0];
            string domainName = str1[1];
            //int index = email.IndexOf('@');
            //string userName = email.Substring(0, index);
            //string domainName = email.Substring(index+1);
            Console.WriteLine("用户名：{0}\n域名：{1}",userName,domainName);
            //4、读取文本
            string path = @"E:\cSharptext1.txt";
            string[] contents = File.ReadAllLines(path, Encoding.Default);
            for (int i = 0; i < contents.Length; i++)
            {
                string[] strNew = contents[i].Split(" ", StringSplitOptions.RemoveEmptyEntries);
                Console.WriteLine((strNew[0].Length>7?strNew[0].Substring(0,7)+"...":strNew[0]) + '|' + strNew[1]);
            }
            //5、用户输入数据，找出所有“  ”的位置
            string userData = Console.ReadLine();
            //int Count1 = 0;
            //for (int i = 0; i < userData.Length; i++)
            //{
            //    if (userData[i]=='我')
            //    {
            //        Count1++;
            //        Console.WriteLine("第{0}次出现的位置是{1}", Count1, i);
            //    }
            //}
            int index = userData.IndexOf('我');         
            int count = 1;//记录出现次数
            Console.WriteLine("第{0}次出现的位置是{1}", count, index);
            //循环体：从上一次出现' '的位置+1的位置找下一次出现' '的位置
            //循环条件：index！=-1
            while (index!=-1)
            {
                count++;
                index = userData.IndexOf('我', index + 1);
                if (index == -1)
                {
                    break;
                }
                Console.WriteLine("第{0}次出现的位置是{1}",count,index);
            }
            //6、"老牛很邪恶"->"老牛很**"
            string s3 = "老牛很邪恶";
            if (s3.Contains("邪恶"))
            {
                s3 = s3.Replace("邪恶", "**");
            }
            Console.WriteLine(s3);
            Console.ReadKey();
        }
    }
}