[c#] How to remove leading and trailing spaces from a string

 static void Main()
    {
        // A.
        // Example strings with multiple whitespaces.
        string s1 = "He saw   a cute\tdog.";
        string s2 = "There\n\twas another sentence.";

        // B.
        // Create the Regex.
        Regex r = new Regex(@"\s+");

        // C.
        // Strip multiple spaces.
        string s3 = r.Replace(s1, @" ");
        Console.WriteLine(s3);

        // D.
        // Strip multiple spaces.
        string s4 = r.Replace(s2, @" ");
        Console.WriteLine(s4);
        Console.ReadLine();
    }

OUTPUT:

He saw a cute dog. There was another sentence. He saw a cute dog.