Convert RTF file content to plain text string

Convert RTF to Plain.cs

string path = @"C:\test\test rich.rtf";

System.Windows.Forms.RichTextBox rtBox = new System.Windows.Forms.RichTextBox();

// Get the contents of the RTF file. Note that when it is
// stored in the string, it is encoded as UTF-16.
string s = System.IO.File.ReadAllText(path);

// Convert the RTF to plain text.
rtBox.Rtf = s;

Console.WriteLine(rtBox.Text);