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• Download source - 4 Kb

Contents

• Introduction
• Using the code
• Class Members
• Thanks to...
• Contacting the Authors

Introduction

This version of file encoder and decoder program is based on the Huffman coding method. It explicitly demonstrates the details of the files during the encoding and decoding. The algorithm is encapsulated in a class En_Decode by the standard C++ language. Here is a demonstration project for the class.

Using the code

This class is implemented by standard C++, so it is very easy to use.

1. Create an MFC application program as usual.
2. Add the source file En_Decode.cpp and En_Decode.h to the project.
3. Add the header file to your project by:

   //
   
   //    #include "En_Decode.h"
   
   //
   
   

   Define your own coder object, such as:

   //
   
   //    En_Decode Coder;
   
   //
   
   

4. Use the member function of the class to set the source file name and destination encoded file name, then call Encode() to encode the source file.

   //
   
   //    Coder.SetInputFileName("C:/test.txt", "txt");
   
   //    Coder.SetOutputFileName("C:/encoded");
   
   //    Coder.Encode();
   
   //
   
   

In the same way, we can decode the encoded files to exactly the source file.

Class Members

Construction

File Name Functions

Paraneter Functions

Thanks to...

Derek Lakin for his help with CTabCtrlSSL in the demo project.

Contacting the Authors

This is the first time I share my code here. It is done in a hurry, so exception handling is ignored. Any one who is interested in it can enhance it freely, and please let me know about any improvement, thanks!

I am a junior student in Huangzhong University of Science and Technology, China. I am interested in C++ and MFC, and any coding project. I am glad to share my codes here with any one, though it is not that good.

Please contact me via email (zxt0123@163.com).

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find some error bansal2945 10:09 4 Dec '08   dear frndz, 1st of all i want to ask that is this algoritham gives same results means can we use this algo on decoding/encoding of ASCii strings. because i have encode a file with ascii char of round length 97. but when i decode this encoded file i find some junk characters. then i tried with some other strings always i found that after 55 chars i was getting right string but from 56's char there were som junk chars. Sign In·View Thread·PermaLink 1.00/5 MFC coding cuty_bujji 2:53 22 Jul '08   how to implement MFC coding to obtain the code words in huffman coding Sign In·View Thread·PermaLink 1.00/5 Is there any other compressing algorithm more efficient than huffman coding wavebai 23:05 9 May '07   Is there any other compressing algorithm more efficient than huffman coding? wavebai Sign In·View Thread·PermaLink 1.33/5 How to compress many files in folder? Newcc 19:12 11 Oct '06   First, thank for your code. But I don't known how to compress many files in a folder into one file compressed only, with extension of file is..., example: *.huf (similar as *.zip) . Program can allow you view files compressed in file *.huf and choice one file in that to uncompress it. It's similar Winzip or Winzar but it's simpler. Can you help me?. Sign In·View Thread·PermaLink 1.80/5 Tab.h beardy janggut 15:45 14 Mar '06   When i compiling the program, a header files is missing. I dont remember the exact header file that missing.It sound like Tab.h. How can i get it from u??? HelpMe Sign In·View Thread·PermaLink 1.00/5 Re: Tab.h cristitomi 3:17 10 Mar '07   Hi! I have downloaded the source code and compiled it and there is no header file missing. You should check it again (perhaps the author has updated the sources). Best regards, Christian. I am in love with VC++ Sign In·View Thread·PermaLink Streaming Compression? andrew2358 6:06 14 Jun '04   One thing I miss from my Java programming days it had a data stream filter that would perform streaming compression (I think with the lzw algorithm). This is the closest thing I've seen in the world of C++/MFC... could it be modified to work as a streaming filter? Perhaps I will take a crack at it. Sign In·View Thread·PermaLink Re: Streaming Compression? Alan Balkany 7:14 14 Jun '04   It may not be possible to use the pure Huffman algorithm to do streaming compression, because Huffman needs to make two passes through the data. The first pass is used to determine the frequency of each byte and build the tree. The second pass does the actual coding. If you knew the approximate frequency distribution of your input, you could build the Huffman tree once, then reuse the same tree for later input streams. i.e. you would skip the first pass. This would give you streaming compression, but if the composition of your input streams changed, you would no longer get optimal compression. Sign In·View Thread·PermaLink Re: Streaming Compression? handychang 19:19 15 Jun '04   Agree! Sign In·View Thread·PermaLink Re: Streaming Compression? John M. Drescher 6:39 16 Jun '04   I would not use this for any real world problem as huffman compression is by no means the best compression algorithm. Huffman compression is used mostly in computer science and maybe math or statistics classes because it is not too difficult to implement compaired to good algorithms like lzw. I would take it more as a learning tool. The big reason why algorithms like lzw (and its variants) are so much better than huffman is that they compress strings of characters into a few bits while huffman only does this for a single character. John -- modified at 8:55 Friday 16th September, 2005 [EDIT] I would like to point out one thing that I did not mention here. The above statement is for lossless compression only as JPEG (original and not JPEG2000) does use huffman but it uses it in a lossy fassion. [/EDIT] Sign In·View Thread·PermaLink 1.00/5 Re: Streaming Compression? Anonymous 6:06 23 Jun '05   That is not true. Huffman has a higher compression capability than LZW because it fully makes use of the frequency distribution throughout the whole sample. LZW doesn't have an overview of the whole sample and therefore it is trying to produce a better compression as it goes along the way. Sign In·View Thread·PermaLink Re: Streaming Compression? John M. Drescher 6:34 23 Jun '05   Ok how does the compression of this application compare to bzip2? LZMA? I will try this myself... [EDIT] I tried the executable from this article, zip and 7zip on the file STLport-5.0-0409.tar which you should still be able to find on the internet. The following is a directory listing of the file compressed by several different programs. Huf is this implementation of huffman. 7z(ip) is LZMA. I assume everybody knows zip. The gz(ip) file was the original I had to run gunzip to get the tar file. I did not bother to do any furthur testing as I stopped after the huf result... 6/24/05 0:20 519,810 STLport-5.0-0409.7z 2/16/02 22:55 748,295 STLport-5.0-0409.tar.gz 6/24/05 0:22 748,415 STLport-5.0-0409.zip 6/24/05 0:23 3,333,596 STLport-5.0-0409.tar.huf 4/10/02 0:51 5,120,000 STLport-5.0-0409.tar [/EDIT] Anonymous wrote: because it fully makes use of the frequency distribution throughout the whole sample. It does do that however because it compresses fixed sized block (of only a few bytes ) into a few bits. While LZW works with variable sized strings which can get much longer into the same few bits. John Sign In·View Thread·PermaLink Re: Streaming Compression? Jan Rodriguez 12:44 19 Oct '06   well, there's adaptive huffman compression, 2 methods: vitter and FGK, i've coded fgk, vitter is a pain in the ass to code, but compresses more the whole point to it is that adaptive huffman coding can be used for streaming, hope it helps Sign In·View Thread·PermaLink Suggestion ! NewGhost 21:46 11 Jun '04   A creative idea! Implementing Huffman Coding in a class provides much convience for us. But I think compressing a string is more useful than compressing a file. Why not providing a class for compressing a string, then we, programmers , put them into a file by our addtional codes ? NewGhost Sign In·View Thread·PermaLink Re: Suggestion ! handychang 21:46 12 Jun '04   Thank you for your suggestion. But I don't understand you quite well. If what you suggest is to encode the string, and then write to the file. Then I think it is unsuitable. Because the encoding method is not efficient for small files, and even if for strings. But after all, thank you for your idea, it reminds me to find another way to think about the question. Thank you! Sign In·View Thread·PermaLink Re: Suggestion ! leandrobecker 10:51 27 Aug '04   Hello I think that he wanna say is to take a buffer to huffman input and the output be a buffer to. Thus allow transmit the buffer over a socket by example ... (Sorry my english, is not my official language Sign In·View Thread·PermaLink Re: Suggestion ! jazzwithshaz 19:30 13 Jan '05   its true i m fully agreed with ur ideas Sign In·View Thread·PermaLink How does Huffman coding work? AORD 17:40 7 Jun '04   Nice article and nice interface. Would be possible to add a short explanation of how the huffman tree compression works. Sign In·View Thread·PermaLink 2.80/5 Re: How does Huffman coding work? handychang 21:55 7 Jun '04   The Huffman coding method is the based on the probabilities of occurence of symbols in the file. This version of coding method first reads the file byte by byte, and record the occurence of each symbol. Then sort the symbols. Then build the Huffman tree. So when a symbol occurs most frequently, we assign one bit to represent it, and two bits for the second frequently one,... and so on. So the file can be compressed. If you still can't understand, I recommend you to read a book about information theorem. It's easy to understand. OK, it's the codes' work to keep the bit stream in order. So we used recursion to impliment it. It takes a little time to understand it. But it does not matter, this algorithm is very classical, you just use it! Sign In·View Thread·PermaLink 3.67/5 Re: How does Huffman coding work? amirhosein 22:15 15 Dec '07   hi you didn't mention any book about the algurithm of huffman coding please, tell me that, i need it to write it by MATLAB yours amirhosein am_semsar@yahoo.com Sign In·View Thread·PermaLink 3.00/5 Picky!!! Paul Charles 6:49 3 Jun '04   GetMinFreq Get the maximum frequency of the symbols in the source file. GetMaxFreq Get the minimum frequency of the symbols in the source file. Spot the mistake!!! Sign In·View Thread·PermaLink 5.00/5 Re: Picky!!! Jubjub 14:30 3 Jun '04   Sign In·View Thread·PermaLink Re: Picky!!! Anonymous 19:22 3 Jul '05   hello Sign In·View Thread·PermaLink 5.00/5 Re: Picky!!! Jubjub 19:45 3 Jul '05   ahoy hoy "If you're too careful, your whole life can become a f---in' grind." - Mike McD (Rounders) Sign In·View Thread·PermaLink Re: Picky!!! handychang 16:20 3 Jun '04   Sorry, I still can't find the mistake. Please point it out clearly. Thanks! Sign In·View Thread·PermaLink 2.00/5

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