Why rd := bufio.NewReader(fi)? 'fi' implements io.Reader. Try: err =
binary.Read(fi, binary.LittleEndian, &pi) instead. Then fi.Seek(...) will
manipulate your io.Reader. [An
example: https://github.com/clbanning/rfile/blob/master/reverse.go#L57.]
On Wednesday, January 18, 2017 at 11:22:48 PM UTC-7, 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
>
>
>
> 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()////?????
>
> err = binary.Read(rd, binary.LittleEndian, &pi)
> if err != nil {
> fmt.Println("binary.Read failed:", err)
> }
> fmt.Println(pi)
>
> }
>
>
--
You received this message because you are subscribed to the Google Groups
"golang-nuts" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to golang-nuts+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
