Determine number of pages in a PDF file

This should do the trick:

public int getNumberOfPdfPages(string fileName)
{
    using (StreamReader sr = new StreamReader(File.OpenRead(fileName)))
    {
        Regex regex = new Regex(@"/Type\s*/Page[^s]");
        MatchCollection matches = regex.Matches(sr.ReadToEnd());

        return matches.Count;
    }
}

From Rachael's answer and this one too.

One Line:

int pdfPageCount = System.IO.File.ReadAllText("example.pdf").Split(new string[] { "/Type /Page" }, StringSplitOptions.None).Count()-2;

Recommended: ITEXTSHARP

You'll need a PDF API for C#. iTextSharp is one possible API, though better ones might exist.

iTextSharp Example

You must install iTextSharp.dll as a reference. Download iTextsharp from SourceForge.net This is a complete working program using a console application.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using iTextSharp.text.pdf;
using iTextSharp.text.xml;
namespace GetPages_PDF
{
  class Program
{
    static void Main(string[] args)
      {
       // Right side of equation is location of YOUR pdf file
        string ppath = "C:\\aworking\\Hawkins.pdf";
        PdfReader pdfReader = new PdfReader(ppath);
        int numberOfPages = pdfReader.NumberOfPages;
        Console.WriteLine(numberOfPages);
        Console.ReadLine();
      }
   }
}

found a way at http://www.dotnetspider.com/resources/21866-Count-pages-PDF-file.aspx this does not require purchase of a pdf library