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<html><head><meta http-equiv="Content-Type"content="text/html; charset=gb_2312-80"><meta name="GENERATOR" content="Microsoft FrontPage Express 2.0"><title>笨笨数据压缩教程</title></head><body bgcolor="#FFFFFF"><p align="right"><a href="../../../index.html">返回断章取义堂</a> <a href="../../index.html">返回咏刚的家</a></p><p style="background-color:#AAEEFF;font-size:14px;color:#0000AA">《笨笨数据压缩教程》是我在1998年因工作需要研究压缩算法时写的文章(算是一种工作笔记吧,其中难免有许多疏漏),1999年初随着项目变迁,就把压缩技术的研究暂时搁置了。从那以后,一是工作太忙,二是自己懒惰,总之是没能把半部压缩教程补全。非常对不住大家。——王咏刚,2003年3月</p><p><img src="benben.jpg"alt="笨笨数据压缩教程(Benben's Data Compression Guide)"width="370" height="129"></p><h2>第六章 聪明的以色列人(下):LZ78 和 LZW</h2><div align="right"><address> <a href="Chapter5.htm">第五章</a> <a href="Chapter7.htm">第七章</a></address></div><p>LZ78 的算法描述:</p><pre>for (;;){ current_match = 1; current_length = 0; memset(test_string, '\0', MAX_STRING); for (;;) { test_string[current_length ++] = getc(input); new_match = find_match(test_string); if (new_match) == -1) break; current_match = new_match; } output_code(current_match); output_char(test_string[current_letgth - 1]; add_string_to_dictionary(test_string);}</pre><p>LZ78 示例:</p><pre>输入正文: "DAD DADA DADDY DADO..."输出短语 输出字符 编码后的串 0 'D' "D" 0 'A' "A" 1 ' ' "D" 1 'A' "DA" 4 ' ' "DA " 4 'D' "DAD" 1 'Y' "DY" 0 ' ' " " 6 'O' "DADO"此时字典的情况:0 ""1 "D"2 "A"3 "D "4 "DA"5 "DA "6 "DAD"7 "DY"8 " "9 "DADO"</pre><p> </p><div align="center"><center><address> <a href="Chapter5.htm">第五章</a> <a href="Chapter7.htm">第七章</a></address></center></div><div align="right"><address> <a href="mailto:wangyg@contextfree.net">有问题吗?有建议吗?快给王笨笨写信</a></address></div><div align="right"><address> <strong>章节书签:</strong><a href="default.htm">前言</a> <a href="content.htm">目录</a> <a href="Chapter1.htm">1</a> <a href="Chapter2.htm">2</a> <a href="Chapter3.htm">3</a> <a href="Chapter4.htm">4</a> <a href="Chapter5.htm">5</a> <a href="Chapter6.htm">6</a> <a href="Chapter7.htm">7</a> <a href="Chapter8.htm">8</a> <a href="Chapter9.htm">9</a> <a href="Chapter10.htm">10</a> <a href="Chapter11.htm">11</a> <a href="Chapter12.htm">12</a> </address></div></body></html>
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