动态串StringBuilder的操作方法

StringBuilder常用的方法:
1.追加:Append, AppendFormat
2.插入:Insert
3.删除:Remove
4.替换:Replace
class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("----------------------------test Append");
            StringBuilder sb = new StringBuilder("Hello",100);
            sb.Append(" World !");
            Console.WriteLine(sb);
            
            Console.WriteLine("----------------------------test Insert");
            sb = new StringBuilder("Hello");
            sb.Insert(2,"sss");
            Console.WriteLine(sb);      //结果为:Hesssllo

            Console.WriteLine("----------------------------test Remove");
            sb = new StringBuilder("Hello");
            sb.Remove(2,3);
            Console.WriteLine(sb);      //结果为:He

            Console.WriteLine("----------------------------test Replace");
            sb = new StringBuilder("Hello");
            sb.Replace("l", "M");
            Console.WriteLine(sb);      //结果为:HeMMo
        }
    }