Extract Text from PDF in C# (100% .NET) - CodeProject

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Introduction

This is a 100% .NET solution to extract text from PDF documents.

Background

Dan Letecky posted a nice code on how to extract text from PDF documents in C# based on PDFBox. Although his solution works well it has a drawback, the size of the required additional libraries is almost 16 MB. Using iTextSharp the size of required additional libraries is only 2.3 MB.

Using the Code

In order to use this solution in your projects, you need to do the following steps:

Add references to itextsharp.dll and SharpZiplib.dll
Add the PDFParser.cs class to your project

Then you can use the newly added class in the following way:

// create an instance of the pdfparser class
PDFParser pdfParser = new PDFParser();
   
// extract the text
String result = pdfParser.ExtractText(pdfFile);

I also created a small console application which uses the class and shows the progress of the conversion. Please keep in mind that if you try to extract text from big PDF files, keeping all the resultant text in memory is not the best solution, in these cases you should write the extracted text to the file after parsing every page.

How Is It Working?

My code is based on the algorithm in C ExtractPDFText. Using iTextSharp's PdfReader class to extract the deflated content of every page, I use a simple function ExtractTextFromPDFBytes to extract the text contents from the deflated page.

Further Improvements

Although the code worked well for me, I didn't find in Adobe's PDF reference how to parse special characters. So if someone knows how to do this, just post it and I will update the class.

History

20^th May, 2006: Initial post

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Zollor

Web Developer

Romania

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No Biography provided

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My vote of 1

20 Jan '12 - 21:35

code is not working
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how to export data from excel to PDF ?

28 Aug '11 - 6:10

Dear all, anybody pls point me the way how can i export data from excel to pdf. or export data from datagridview to pdf that support unicode string.. feel is very complicated serveral days ago but can't find any solution.. pls help me
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not work

1 Aug '11 - 14:45

very simple feedback : it does not work !
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Dosn't work.

29 Jun '11 - 19:13

I couldn't extract text from pdf. I have just download the coding and include the dll file and PDFSharper file to my project but i didn't get any string in output file. Anybody please help me. Thanks in advance..
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Alternate Solution

7 May '11 - 3:44

The iTextSharp.dll that is included with this project bombed when I ran the program on a test file that I created with Acrobat X. The latest version of iTextSharp works better. The program itself works sort of with PDF files created with ABBYY, but it does not interpret all the tokens correctly. The result is unwanted spaces within the text. While looking for an explanation of the tokens that are embedded in the stream, I came arcross http://www.java2s.com/Open-Source/CSharp/PDF/iTextSharp/iTextSharp/text/pdf/parser/Catalogparser.htm. It has the source that compiles to a program that not only extracts the text, but also lists the dictionary and content stream. The only drawback is that you have to copy and paste 26 files into Visual Studio since I have not been able to find a download link, but it does what I needed it to do and more.

Re: Alternate Solution

2 Feb '12 - 9:04

This code is actually in the latest version of iTextSharp (5.1.3.0) and is much simpler to use than the code in this project (and works more reliably too). Here's a simple class that uses iTextSharp:

using System;
using iTextSharp.text.pdf;
using iTextSharp.text.pdf.parser;
 
public class PdfTextParser
{
    public string ExtractTextFromPDFPage(string pdfFile, int pageNumber)
    {
        PdfReader reader = new PdfReader(pdfFile);
        string text = PdfTextExtractor.GetTextFromPage(reader, pageNumber);
        try { reader.Close(); }
        catch {}
        return text;
    }
}

Re: Alternate Solution

13 Feb '12 - 15:45

Wow, thank you! This works perfectly and requires quite a bit less code.
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Re: Alternate Solution

14 Aug '12 - 13:45

Works for me!
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(Solved) Error when reading some document (page missing)

8 Apr '11 - 0:13

Thanks you very much for your CODE! Thumbs Up | :thumbsup:

Thumbs Up | :thumbsup:

Thumbs Up | :thumbsup:

Thumbs Up | :thumbsup:

you saved my ass on my current project when PDFBox fail to extract the text! Cool | :cool:

Cool | :cool:

Cool | :cool:

I encounter some problem reading some pages of some document anyway
because in the code (method ExtractTextFromPDFBytes)you call:

if (CheckToken(new string[] {"'", "T*", "\""}, previousCharacters))
{
         resultString += "\n";
}

But the CheckToken take for granted that ALL tokens are 2 character long at least

if ((recent[_numberOfCharsToKeep - 3] == token[0]) &&
   (recent[_numberOfCharsToKeep - 2] == token[1]) &&
...

checking if the token is long 1 character or more solve the problem.

you need to change the CheckToken method with this one:

private bool CheckToken(string[] tokens, char[] recent)
        {
            foreach(string token in tokens)
            {
                if (token.Length > 1)
                {
                    if ((recent[_numberOfCharsToKeep - 3] == token[0]) &&
                        (recent[_numberOfCharsToKeep - 2] == token[1]) &&
                        ((recent[_numberOfCharsToKeep - 1] == ' ') ||
                        (recent[_numberOfCharsToKeep - 1] == 0x0d) ||
                        (recent[_numberOfCharsToKeep - 1] == 0x0a)) &&
                        ((recent[_numberOfCharsToKeep - 4] == ' ') ||
                        (recent[_numberOfCharsToKeep - 4] == 0x0d) ||
                        (recent[_numberOfCharsToKeep - 4] == 0x0a))
                        )
                    {
                        return true;
                    }
                }
                else
                {
                    if ((recent[_numberOfCharsToKeep - 2] == token[0]) &&
                        ((recent[_numberOfCharsToKeep - 1] == ' ') ||
                        (recent[_numberOfCharsToKeep - 1] == 0x0d) ||
                        (recent[_numberOfCharsToKeep - 1] == 0x0a)) &&
                        ((recent[_numberOfCharsToKeep - 4] == ' ') ||
                        (recent[_numberOfCharsToKeep - 4] == 0x0d) ||
                        (recent[_numberOfCharsToKeep - 4] == 0x0a))
                        )
                    {
                        return true;
                    }
                }
            }
            return false;
        }

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Re: (Solved) Error when reading some document (page missing) [modified]

22 Jun '11 - 7:40

Thanks for pointing this out

The CheckToken method seems to find [whitespace][token_chars][whitespace] at the end of recent

So when tokens[i] contains 2 characters (from -4 to -1) :

	(
		(recent[_numberOfCharsToKeep - 4] == ' ')
		|| (recent[_numberOfCharsToKeep - 4] == 0x0d)
		|| (recent[_numberOfCharsToKeep - 4] == 0x0a)
	)
	&& (recent[_numberOfCharsToKeep - 3] == token[0])
	&& (recent[_numberOfCharsToKeep - 2] == token[1])
	&& (
		(recent[_numberOfCharsToKeep - 1] == ' ')
		|| (recent[_numberOfCharsToKeep - 1] == 0x0d)
		|| (recent[_numberOfCharsToKeep - 1] == 0x0a)
	)

But when tokens[i] contains 1 character, it should be (from -3 to -1) :

	(
		(recent[_numberOfCharsToKeep - 3] == ' ')
		|| (recent[_numberOfCharsToKeep - 3] == 0x0d)
		|| (recent[_numberOfCharsToKeep - 3] == 0x0a)
	)
	&& (recent[_numberOfCharsToKeep - 2] == token[0])
	&& (
		(recent[_numberOfCharsToKeep - 1] == ' ')
		|| (recent[_numberOfCharsToKeep - 1] == 0x0d)
		|| (recent[_numberOfCharsToKeep - 1] == 0x0a)
	)

Right ?

modified on Wednesday, June 22, 2011 1:47 PM

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A simple class to extract plain text from PDF documents with ITextSharp

Type	Article
Licence	CPOL
First Posted	20 May 2006
Views	267,468
Downloads	34,186
Bookmarked	141 times

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