为什么使用unix-compress和go compress / lzw会生成其他解码器无法读取的不同文件？

问题描述：

I compressed a file in a terminal with compress file.txt and got (as expected) file.txt.Z

When I pass that file to ioutil.ReadFile in Go,

buf0, err := ioutil.ReadFile("file.txt.Z")

I get the error (the line above is 116):

finder_test.go:116: lzw: invalid code

I found that Go would accept the file if I compress it using the compress/lzw package, I just used code from a website that does that. I only modified the line

outputFile, err := os.Create("file.txt.lzw")

I changed the .lzw to .Z. then used the resulting file.txt.Z in the Go code at the top, and it worked fine, no error.

Note: file.txt is 16.0 kB, unix-compressed file.txt.Z is 7.8 kB, and go-compressed file.txt.Z is 8.2 kB

Now, I was trying to understand why this happened. So, I tried to run

uncompress.real file.txt.Z

and it did not work. I got

file.txt.Z: not in compressed format

I need to use a compressor (preferably unix-compress) to compress files using lzw-compression then use the same compressed files on two different algorithms, one written in C and the other in Go, because I intend to compare the performance of the two algorithms. The C program will only accept the files compressed with unix-compress and the Go program will only accept the files compressed with Go's compress/lzw.

Can someone explain why that happened? Why are the two .Z files not equivalent? How can I overcome this?

Note: I am working on Ubuntu installed in VirtualBox on a Mac.

我在终端中使用compress file.txt code>压缩了文件并得到了（如预期的那样）） file.txt.Z code> p>

当我将该文件传递给Go中的 ioutil.ReadFile code>时， p> \ n

  buf0，err：= ioutil.ReadFile（“ file.txt.Z”）
  code>  pre> 
 
 我得到了错误（上面的行是 116）： p> 
 
 
  finder_test.go：116：lzw：无效代码
  code>  pre> 
 
 我发现Go会接受 如果我使用 compress / lzw  code>包压缩文件，则我只是使用了执行此操作的网站。 我只修改了这一行 p> 
 
 
  outputFile，err：= os.Create（“ file.txt.lzw”）
  code>  pre> 
 
  我将 .lzw  code>更改为 .Z  code>。 然后在顶部的Go代码中使用生成的 file.txt.Z  code>，它工作正常，没有错误。 p> 
 
 
注意： file。  txt  code>是16.0 kB，unix压缩的 file.txt.Z  code>是7.8 kB，go压缩的 file.txt.Z  code>是8.2 kB  p  > 
 
 
现在，我正试图了解发生这种情况的原因。 因此，我尝试运行 p> 
 
 

  uncompress.real file.txt.Z 
  code>  pre> 
 
 ，但此方法不起作用 。 我得到了 p> 
 
 
  file.txt.Z：不是压缩格式
  code>  pre> 
 
 我需要使用压缩器（ 最好使用 unix-compress  code>）来使用 lzw-compression  code>压缩文件，然后对两种不同的算法使用相同的压缩文件，一种是用C编写的，另一种是用Go编写的，因为我打算 比较两种算法的性能。   C  code>程序将仅接受使用 unix-compress  code>压缩的文件，而Go程序将仅接受使用Go的 compress / lzw  code>压缩的文件。   p> 
 
 
有人可以解释为什么会这样吗？ 为什么两个.Z文件不相等？ 我该如何克服呢？ p> 
 
 

注意：我正在Mac上安装在VirtualBox中的Ubuntu上。 p> 
  div>

答

A .Z file does not only contain LZW compressed data, there is also a 3-bytes header that the Go LZW code does not generate because it is meant to compress data, not generate a Z file.

答

Presumably you only want to test the performance of two of your/some third party algorithms (& not the compression algorithms themselves), you may want to write a shell script which calls the compress command passing the files/dir's required and then call this script from your C / GO program. This is one way you can overcome this, but leaves open other parts of your queries on the correct way to use the compression libraries.

为什么使用unix-compress和go compress / lzw会生成其他解码器无法读取的不同文件？

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