If all you need is to display the file, the simplest way is to use a WebBrowser control like:
string path = @"C:\1\C# Threading Handbook.pdf";
System.Diagnostics.Process.Start("IExplore.exe", path);
or can open it with default viewer (adobe reader):
string filePath = @"C:\1\C# Threading Handbook.pdf";
string adobeReaderPath = @"C:\Program Files\Adobe\Reader 10.0\Reader\AcroRd32.exe";
System.Diagnostics.Process.Start(adobeReaderPath, filePath);
Also can view:
How to Show PDF file in C#[
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Displaying a pdf file from Winform[
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