public void ExtractTextInfo()
{
    //Initialize the SDK library
    //You have to call this function before you can call any PDF processing functions.
    PdfCommon.Initialize();

    //Open and load a PDF document from a file.
    using (var doc = PdfDocument.Load(@"c:\test001.pdf"))
    {
        //Get second page from document
        using (var page = doc.Pages[1])
        {
            //Extract text information structure from the page
            // 10 - Index for the start characters
            // 25 - Number of characters to be extracted
            var textInfo = page.Text.GetTextInfo(10, 25);

            //Gets text from textInfo strtucture
            string text = textInfo.Text;

            //Gets a collection of rectangular areas bounding specified text.
            var rects = textInfo.Rects;
        }
    }

    //Release all resources allocated by the SDK library
    PdfCommon.Release();
}