I am using bufio.Reader and binary.Read
to read binary from file, I want to seek in the file or bufio.Reader
Below code does not work
fi.Seek(0, os.SEEK_SET) ////Does not work for bufio.Reader
below definition shows that r control the position , but I did not see any
method to set it
type Reader struct {
buf []byte
rd io.Reader // reader provided by the client
r, w int // buf read and write positions
err error
lastByte int
lastRuneSize int
}
I expect below code to output 3.13 twice , but it output 3.13 3.14
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) ////Does not work for bufio.Reader
err = binary.Read(rd, binary.LittleEndian, &pi)
if err != nil {
fmt.Println("binary.Read failed:", err)
}
fmt.Println(pi)
}
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