string s = Console.ReadLine();
do
{
#region
if (num == 1)
{
Console.WriteLine("请输入要哪里追加的字符串是什么");
int index = Convert.ToInt32(Console.ReadLine());
string newword = Console.ReadLine();
sb.Insert(index, newword);
sb.AppendLine();
Console.WriteLine(sb);
Console.WriteLine("继续？（y/n）");
}
else if (num == 2)
{
Console.WriteLine("请输入要提取的字符串的位置和个数");
int index = Convert.ToInt32(Console.ReadLine());
int coun = Convert.ToInt32(Console.ReadLine());
string input = sb.ToString();
Console.WriteLine(input.Substring(index, coun));
Console.WriteLine("继续？（y/n）");
}
else if (num == 3)
{
Console.WriteLine("请输入要替换的字符串:");
string word = Console.ReadLine();
Console.WriteLine("替换为：");
string newword = Console.ReadLine();
sb.Replace(word, newword);
Console.WriteLine("替换后结果：{0}",sb);
Console.WriteLine("继续？（y/n）");
}
else if (num == 4)
{
string patter = @"(\d+)|([a-z])";
string word = sb.ToString();
if (Regex.IsMatch(word, patter))
{
Console.WriteLine("包含了非汉字");
}
else
{
Console.WriteLine("不包含数字和小写字母");
}
Console.WriteLine("继续？（y/n）");
;
}
else if (num == 5)
{
Console.WriteLine("请输入要移除的指定位子：");
int index = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("删除的个数");
int c = Convert.ToInt32(Console.ReadLine());
sb.Remove(index, c);
Console.WriteLine("删除后的结果：{0}", sb);
Console.WriteLine("继续？（y/n）");
}
else
{
Console.WriteLine("不包含该操作");
}
#endregion
} while (s == "y"||s=="Y");
