C#字符串(Sring)操作

　　　　//字符串访问
            //string s = "ABCD";
            //Console.WriteLine(s[0]);//第0位字符
            //Console.WriteLine(s.Length);//字符串长度
            //-----------------------------------------------------------
            //打散
            //string s = "ABCD";
            //char[] arr = s.ToCharArray();//将字符串打散,并放入字符数组中.
            //Console.WriteLine(arr[0]);//arr[0]='A',arr[1]='B',arr[2]='C',arr[3]='D'
            //-----------------------------------------------------------
            //截取
            //string s = "ABCD";
            //Console.WriteLine(s.Substring(1));//从第二位开始截取到最后一位,显示BCD
            //Console.WriteLine(s.Substring(2, 2));//从第三位开始截取二个,显示CD           
            //-----------------------------------------------------------
            //字符匹配
            //string s = "ABCABCD";
            //Console.WriteLine(s.IndexOf('A'));//找到该字符,返回所在位置.输出0
            //Console.WriteLine(s.IndexOf("BCD"));//找到该串,返回头所在位置.输出4
            //Console.WriteLine(s.IndexOf('E'));//当找不到任何相关的匹配时,输出-1;
            //Console.WriteLine(s.LastIndexOf('C'));//从末尾开始匹配,输出5
            //Console.WriteLine(s.LastIndexOf("AB"));//同上,输出3
            //Console.WriteLine(s.Contains("ABCD"));//判断此字符串是不是在另一字符串匹配
            //-----------------------------------------------------------
            //大小写转换
            //string s = "aBcD";
            //Console.WriteLine(s.ToLower());//将字符串转为小写,输出abcd
            //Console.WriteLine(s.ToUpper());//将字符串将为大小,输出ABCD
            //-----------------------------------------------------------
            //匹配移除
            //string s = "_@$_AB__CD_$@_";
            //Console.WriteLine(s.Trim('_'));//移除首和尾匹配字符,输出@$_AB__CD_$@
            //Console.WriteLine(s.TrimStart('_'));//移除首部字符,输出@$_AB__CD_$@_
            //Console.WriteLine(s.TrimEnd('_'));//移除尾部字符,输出_@$_AB__CD_$@
            //Console.WriteLine(s.Trim('_', '@', '$'));//只能移除字符,可以写很多..输出AB__CD
            //-----------------------------------------------------------
            //插入和删除
            //string s = "ADEF";
            //Console.WriteLine(s.Insert(1, "BC"));//在字符串什么位置插入字符串,输出ABCDEF
            //Console.WriteLine(s.Remove(1));//从字符串第二个位开始到最后的字符都删除,输出A
            //Console.WriteLine(s.Remove(0, 2));//从第一位开始删除二个字符,输出EF
            //-----------------------------------------------------------
            //替换
            //string s = "A_B_C_D";
            //Console.WriteLine(s.Replace('_', ':'));输出A:B:C:D
            //Console.WriteLine(s.Replace("_", ""));//只有字符串才能替换空字符,输出ABCD
            //-----------------------------------------------------------
            //分割
            //string s = "A,B,C,D";
            //string[] arr = s.Split(',');
            //Console.WriteLine(arr[0]);输出A
            //Console.WriteLine(arr[1]);输出B
            //Console.WriteLine(arr[2]);输出C
            //Console.WriteLine(arr[3]);输出D
            //-----------------------------------------------------------
            //连接
            //string[] arr = new string[] { "A", "B", "C", "D" };
            //Console.WriteLine(string.Concat(arr));//连接字符串数组
            //Console.WriteLine(string.Join(",", arr));//连接字符串数组,并带有分隔
            //StringBuilder stringBuilder = new StringBuilder();//一种很高效的连接字符串的方式
            //stringBuilder.Append(arr[0]);
            //stringBuilder.Append(arr[1]);
            //stringBuilder.Append(arr[2]);
            //stringBuilder.Append(arr[3]);
            //Console.WriteLine(stringBuilder.ToString());