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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