C＃正则表达式发出“无法识别的转义序列”

static void Main(string[] args)

    {
        //string pattern1 = \"xxx-xxx-xxxx\";
        //string pattern2 = \"xxx.xxx.xxxx\";
        //string pattern3 = \"(xxx) xxx-xxxx\";

        string[] fileEntries = Directory.GetFiles(@\"C:\\BTISTestDir\");

        foreach (string filename in fileEntries)
        {
            StreamReader reader = new StreamReader(filename);
            string content = reader.ReadToEnd();
            reader.Close();

            string regexPattern1 = \"^(\\d{3}\\.){2}\\d{4}$\";
            string regexPattern2 = \"^((\\(\\d{3}\\) ?)|(\\d{3}-))?\\d{3}-\\d{4}$\";

            if(Regex.IsMatch(content, regexPattern1))
                Console.WriteLine(\"File found: \" + filename);
            if(Regex.IsMatch(content, regexPattern2))
                Console.WriteLine(\"File found: \" + filename);
        }

        Console.WriteLine(Environment.NewLine + \"Finished\");
        Console.ReadLine();
    }