package main

import (
	"fmt"
	"io/ioutil"
	"os"
)

func main() {
	fmt.Println("Hello, playground")
	data := []byte{65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 0, 0, 0, 0, 0, 0, 0, 0}
	fileNm := "test"
	ioutil.WriteFile(fileNm, data, 0644)
	rslt, _ := ioutil.ReadFile(fileNm)
	fmt.Println("string:", string(rslt), ", []byte:", rslt, ", length:", len(rslt))
	f, _ := os.Open(fileNm)
	defer f.Close()
	info, _ := f.Stat()
	lo := int64(0)
	hi := info.Size() - 1
	var buf [1]byte
	for lo <= hi {
		mid := (lo + hi) / 2
		f.ReadAt(buf[:], mid)
		if buf[0] == byte(0) {
			hi = mid - 1
		} else {
			lo = mid + 1
		}
	}
	if lo != info.Size() {
		os.Truncate(fileNm, lo)
	}
	rslt, _ = ioutil.ReadFile(fileNm)
	fmt.Println("string:", string(rslt), ", []byte:", rslt, ", length:", len(rslt))
}