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.
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？
I compressed a file in a terminal with
compress file.txt and got (as expected)
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
.Z. then used the resulting
file.txt.Z in the Go code at the top, and it worked fine, no error.
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
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
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.
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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.点赞 评论 复制链接分享