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64-reading-files.go
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/
64-reading-files.go
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package main
import (
"bufio"
"fmt"
"io"
"os"
)
func check(e error){
if e != nil {
panic(e)
}
}
func main(){
dat, err := os.ReadFile("./tmp/dat")
check(err)
fmt.Println(string(dat))
f, err := os.Open("./tmp/dat")
check(err)
b1 := make([]byte, 5)
n1, err := f.Read(b1)
check(err)
fmt.Printf("%d bytes: %s\n",n1, string(b1[:n1]))
o2,err := f.Seek(6, io.SeekStart)
check(err)
b2 := make([]byte,2)
n2,err := f.Read(b2)
check(err)
fmt.Printf("%d bytes @ %d: ",n2,o2)
fmt.Printf("%v\n",string(b2[:n2]))
_,err = f.Seek(4, io.SeekCurrent)
check(err)
_,err = f.Seek(-10,io.SeekEnd)
check(err)
o3,err := f.Seek(6,io.SeekStart)
check(err)
b3 := make([]byte,2)
n3, err := io.ReadAtLeast(f, b3, 2)
check(err)
fmt.Printf("%d bytes @ %d: %s\n",n3,o3,string(b3))
_,err = f.Seek(0,io.SeekStart)
check(err)
r4 := bufio.NewReader(f)
b4, err := r4.Peek(5)
check(err)
fmt.Printf("5 bytes: %s\n",string(b4))
f.Close()
}