调试Python的zlib和golang的zlib之间的差异。为什么以下代码没有相同的结果?
Python版本的第五个字节为
compress.go
:package main
import (
"compress/flate"
"bytes"
"fmt"
)
func compress(source string) []byte {
w, _ := flate.NewWriter(nil, 7)
buf := new(bytes.Buffer)
w.Reset(buf)
w.Write([]byte(source))
w.Close()
return buf.Bytes()
}
func main() {
example := "foo"
compressed := compress(example)
fmt.Println(compressed)
}
compress.py
:
from __future__ import print_function
import zlib
def compress(source):
# golang zlib strips header + checksum
compressor = zlib.compressobj(7, zlib.DEFLATED, -15)
compressor.compress(source)
# python zlib defaults to Z_FLUSH, but
# https://golang.org/pkg/compress/flate/#Writer.Flush
# says "Flush is equivalent to Z_SYNC_FLUSH"
return compressor.flush(zlib.Z_SYNC_FLUSH)
def main():
example = u"foo"
compressed = compress(example)
print(list(bytearray(compressed)))
if __name__ == "__main__":
main()
结果
$ go version
go version go1.7.3 darwin/amd64
$ go build compress.go
$ ./compress
[74 203 207 7 4 0 0 255 255]
$ python --version
$ python 2.7.12
$ python compress.py
[74, 203, 207, 7, 0, 0, 0, 255, 255]
Python版本的第五个字节为
0
,但golang版本为4
-- 是什么导致了不同的输出?
Flush()
,则输出将相同。还要注意,不同的实现不能保证产生相同的二进制输出,它们只能保证产生兼容的输出。 - JimBw.Write(...)
行后添加显式的w.Flush()
会增加更多的填充/校验和字节。您能否提供更多细节,因为显然有些事情我没有理解? - everial