c# routines to search pdf files

Two ideas for you:

(1) iTextSharp is the .NET port of iText:
http://sourceforge.net/projects/itextsharp/

It is a robust library for working with PDF files, and it is geared towards C# (while iText towards Java).

(2) Xpdf is a set of eight command line executables:
http://www.foolabs.com/xpdf/

The only one you'll need is pdftotext.exe, which converts PDF files to plain text. You may download the package here:
http://www.foolabs.com/xpdf/download.html

To learn more about downloading/installing it, I suggest watching Xpdf - Command Line Utility for PDF Files - Part 1, a 5-minute Experts Exchange video Micro Tutorial:
https://www.experts-exchange.com/VP_213.html

Another 5-minute EE video Micro Tutorial, Xpdf - Convert PDF Files to Plain Text Files - Part 3, explains the specific tool you need, PDFtoText:
https://www.experts-exchange.com/VP_217.html

Other parts of my Xpdf video series are not relevant for this particular project, but here they are in case you need them for future projects:

Xpdf - Extract Images from PDF Files - Part 2
https://www.experts-exchange.com/VP_215.html

Xpdf - PDFinfo - Command Line Utility to Retrieve Page Count and Other Information from PDF Files
https://www.experts-exchange.com/videos/1098/

Xpdf - PDFdetach - Command Line Utility to Detach Attachments from PDF Files
https://www.experts-exchange.com/videos/1118/

There are five different options for creating the text in PDFtoText:

-layout
-lineprinter
-raw
-table
<null>, which is the default

I find that -layout usually works best for me, but you should experiment with your particular PDFs to see which output option creates files that work best in your program. Regards, Joe

Thank-you. Your response was very helpful. What I have is thousands of PDF's that are copies of emails. I want to be able to extract the FROM:, TO:, SUBJECT etc. What I believe you are pointing me to is that I will need to convert the PDF to text, and then interrogate the text for the answers. If there is a simpler solution or any c# code that maps this out that you know of it would be appreciated, otherwise, I will keep trying to figure it out myself. Thanks again for your help.