Huffman Coding Class

handychang

4.17/5 (20 votes)

Jun 3, 2004

CPOL

2 min read

221210

10403

A file compressor class based on the Huffman Tree

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.

Create an MFC application program as usual.
Add the source file En_Decode.cpp and En_Decode.h to the project.
Add the header file to your project by:
```
//
//    #include "En_Decode.h"
//
```
Define your own coder object, such as:
```
//
//    En_Decode Coder;
//
```
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

En_Decode Constructs a En_Decode object.

File Name Functions

`SetInputFileName`	Set the input file name.
`SetOutputFileName`	Set the output file name.
`GetExtName`	Get the ext name of the encoded file when decoding.

Paraneter Functions

`GetMinFreq`	Get the minimum frequency of the symbols in the source file.
`GetMaxFreq`	Get the maximum frequency of the symbols in the source file.
`GetFreq(idx)`	Get the frequency value of a symbol in the source file.
`GetActiveSymbols`	Get the number of active symbols in the source file.
`GetActualDataLength`	Get the bytes number of the encoded file not including head.
`GetUncodedFileLength`	Get the length of the source file.
`GetEncodedFileCodeLength`	Get the average code length of the encoded file.
`GetSourceFileEntropy`	Get the entropy of the source file.

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).