Reading Files

packagemain

import (

    "bufio"

    "fmt"

    "io"

    "io/ioutil"

    "os"

)

func check(e error) {

    if e != nil {

        panic(e)

    }

}

func main() {

    dat, err := ioutil.ReadFile("/tmp/dat")

    check(err)

    fmt.Print(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))

    o2, err := f.Seek(6, 0)

    check(err)

    b2 := make([]byte, 2)

    n2, err := f.Read(b2)

    check(err)

    fmt.Printf("%d bytes @ %d: %s\n", n2, o2, string(b2))

    o3, err := f.Seek(6, 0)

    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, 0)

    check(err)

    r4 := bufio.NewReader(f)

    b4, err := r4.Peek(5)

    check(err)

    fmt.Printf("5 bytes:%s\n", string(b4))

    f.Close()

}