so the file seek does not work in bufio.Read ?
在 2017年1月19日星期四 UTC+8下午2:59:39，hui zhang写道：
>
> fi.Seek(0, os.SEEK_SET )////?????
>
>
> I set this in the code and I expected to print 3.13 twice , but this code
> print 3.13 3.14
> why?
>
> package main
>
> import (
> _ "bytes"
> "fmt"
> _ "math"
>
> "bufio"
> "encoding/binary"
> "os"
> )
>
> func main() {
> var pi float64
> //b := []byte{0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40,
> // 0x78, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40}
> //buf := bytes.NewReader(b)
> //err := binary.Read(buf, binary.LittleEndian, &pi)
> //if err != nil {
> // fmt.Println("binary.Read failed:", err)
> //}
> //fmt.Println(pi)
> //// Output: 3.141592653589793
> //err = binary.Read(buf, binary.LittleEndian, &pi)
> //if err != nil {
> // fmt.Println("binary.Read failed:", err)
> //}
> //fmt.Println(pi)
> //------------------------------------------------------------
> // open output file
> fo, err := os.Create("./output.bin")
> if err != nil {
> panic(err)
> }
>
> // make a write buffer
> var fl1 float64 = 3.13
> var fl2 float64 = 3.14
> w := bufio.NewWriter(fo)
> err = binary.Write(w, binary.LittleEndian, fl1)
> if err != nil {
> fmt.Println("binary.Write failed:", err)
> }
> err = binary.Write(w, binary.LittleEndian, fl2)
> if err != nil {
> fmt.Println("binary.Write failed:", err)
> }
> w.Flush()
> // close fo on exit and check for its returned error
> if err := fo.Close(); err != nil {
> panic(err)
> }
>
> //------------------------------------------------------------
> fi, err := os.Open("./output.bin")
> if err != nil {
> panic(err)
> }
> // close fi on exit and check for its returned error
> defer func() {
> if err := fi.Close(); err != nil {
> panic(err)
> }
> }()
>
> rd := bufio.NewReader(fi)
> err = binary.Read(rd, binary.LittleEndian, &pi)
> if err != nil {
> fmt.Println("binary.Read failed:", err)
> }
> fmt.Println(pi)
>
> fi.Seek(0, os.SEEK_SET )////?????
>
> err = binary.Read(rd, binary.LittleEndian, &pi)
> if err != nil {
> fmt.Println("binary.Read failed:", err)
> }
> fmt.Println(pi)
>
> }
>
>
> 在 2017年1月19日星期四 UTC+8下午2:43:31，Ayan George写道：
>>
>>
>>
>> On 01/19/2017 01:22 AM, hui zhang wrote:
>> > I am using encoding/binary to read/write (struct)data to/from file.
>> > Some times , I need to seek in the file while reading .
>> > how to do this in go.
>> > Check the code below
>>
>> [snip!]
>> >
>> >
>> > fi, err := os.Open("./output.bin")
>> > if err != nil {
>> > panic(err)
>> > }
>> > // close fi on exit and check for its returned error
>> > defer func() {
>> > if err := fi.Close(); err != nil {
>> > panic(err)
>> > }
>> > }()
>> >
>> > rd := bufio.NewReader(fi)
>> > err = binary.Read(rd, binary.LittleEndian, &pi)
>> > if err != nil {
>> > fmt.Println("binary.Read failed:", err)
>> > }
>> > fmt.Println(pi)
>> >
>> > fi.seek()////?????
>> >
>>
>> Is File.Seek() what you're looking for or do you need something else?
>>
>> https://golang.org/pkg/os/#File.Seek
>>
>> -ayan
>>
>>
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