optimise files

CS/15_8/Program.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Text.RegularExpressions;
+
+namespace _15_8
+{
+    internal class Program
+    {
+        static void Main(string[] args)
+        {
+            string strIn = @"~@ How are you doing? Fine，thanks！";
+            string result = Regex.Replace(strIn, @"[^\w\. ?,]", "");
+            Console.WriteLine(strIn);
+            Console.WriteLine(result);
+        }
+    }
+}