文件压缩是有用,当传输非常大的文件。每个字符的Ascii文本文件编码由一个8位固定长度的代码。这些文件通常可以大大压缩,如果不是这个固定长度的代码使用一个变量长度代码更频繁出现字符有短码和更少的字符有较长的代码出现。例如,一个大型数据文件可能主要是数字、空间和换行字符。如果短(小于8位)编码是用于这些然后文件将大大压缩。一个Lisp文件可能有很多左和右括号在它。使用短代码对这些将压缩文件。使用霍夫曼编码压缩文件。-File compression is useful when the transmission is very large files. Each character in the Ascii text files encoded by a 8 bits of fixed length code. These files can usually be greatly compressed, if not the fixed length code USES a variable length code more frequent characters have short code and fewer characters have longer code. For example, a large data file may major is digital, space, and newline characters. In case there is short (less than 8) encoding is used for the file will then compression greatly. A Lisp files may have many left and right parentheses in it. Use short code for these will be compressed file. Use Huffman coding compressed files.