去gzip不输出预期的输出

Question

I'm trying to compress a string with Gzip and uncompress it, but it doesn't work as I expected.

My code is the following where I compress "hello World" and then read/decompress it

  s := []byte("hello world")

  var b bytes.Buffer
  gz := gzip.NewWriter(&b)
  defer gz.Close()
  _, err = gz.Write(s)
  if err != nil {
    panic(err)
  }

  r, err := gzip.NewReader(&b)
  defer r.Close()
  if err != nil {
    panic(err)
  }

  l, _ := r.Read(s)

  log.Println(l)

I expect it to return "hello world" but it returns 0..

If I remove l, _ := r.Read(s) and replace the last line with log.Println(r) I get this which doesn't quite makes sense

&{{ [] 2042-07-14 02:04:00 +0100 CET  255} 0x1847b780 0x185aa000 0x18400db8 0 0 [31 139 8 0 0 9 110 136 0 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] <nil>}

Can someone explain me where I'm wrong?

What I want is just compress a string and return its decompressed result later.

Answer 1

Finish writing the output. For example,

package main

import (
    "bytes"
    "compress/gzip"
    "log"
)

func main() {
    var b bytes.Buffer

    w := gzip.NewWriter(&b)
    s := []byte("hello world")
    _, err := w.Write(s)
    if err != nil {
        panic(err)
    }
    err = w.Flush()
    if err != nil {
        panic(err)
    }
    err = w.Close()
    if err != nil {
        panic(err)
    }

    r, err := gzip.NewReader(&b)
    if err != nil {
        panic(err)
    }
    defer r.Close()
    t := make([]byte, len(s))
    l, err := r.Read(t)
    if err != nil {
        panic(err)
    }

    log.Println(l, string(t))
}

Output:

2009/11/10 23:00:00 11 hello world