TX Text Control is not only able to load and modify MS Word documents such as DOC, RTF and DOCX files. TX Text Control is also able to import "born digital" PDF documents, so that you can view, edit or convert these files.

An overview of the features and the possibilities can be read here:

PDF Reflow - Load, view, edit and convert Adobe PDF files

The combination of ServerTextControl, LINQ and regular expressions provides a powerful tool to search strings in PDF documents. The method FindInPDF listed below accepts a PDF document as a file path and a value to seek. ServerTextControl opens the PDF in order to provide the plain text to a regular expression.

The resulting MatchCollection of the Matches method is used by LINQ to return the index of each individual result that are stored in an IEnumerable<int> object.

private IEnumerable<int> FindInPDF(string path, string value)
{
    string sSourceString = "";

    // create a temporary ServerTextControl that imports the PDF file
    using (TXTextControl.ServerTextControl tx =
        new TXTextControl.ServerTextControl())
    {
        TXTextControl.LoadSettings ls= new TXTextControl.LoadSettings();
        ls.PDFImportSettings = TXTextControl.PDFImportSettings.GenerateLines;

        tx.Create();
        tx.Load(path, TXTextControl.StreamType.AdobePDF, ls);

        // prepare the string to match the numbers of
        // control chartacters
        sSourceString = tx.Text.Replace("
","
"); 
    }

    // use RegEx and LINQ to match the strings and to return the ID
    return
        Regex.Matches(sSourceString, value).Cast<Match>().Select(m => m.Index);
}

The following code returns all index positions of the string "text" in a PDF document:

IEnumerable<int> index = FindInPDF("test.pdf", "text");