fileoperations.go

package main

import (
	"fmt"
	"io"
	"os"
)

const (
	fromFileName = "values.json"
	toFileName   = "values_copy.json"
)

func getFileReader() io.Reader {
	fromFileReader, err := os.OpenFile(fromFileName, os.O_RDONLY, 0666)
	defer fromFileReader.Close()
	if err != nil {
		fmt.Println("There is error in reading file contents!", err)
	}
	return fromFileReader
}

func writeToFile(reader io.Reader, writer io.Writer)  (int64, error){
	return io.Copy(writer, reader)
}

func main() {
	toFileWriter, err := os.OpenFile(toFileName, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0666)
	if err != nil {
		fmt.Println("There is error in file creation!", err)
	}
	defer toFileWriter.Close()

	fromFileReader := getFileReader()

	_, err = writeToFile(fromFileReader, toFileWriter)
	if err != nil {
		fmt.Println("There is error in writing file contents! ", err)
	}
	// err = toFileWriter.Sync()
	// if err != nil {
	// 	fmt.Println("There is error  flushing in memory contents ", err)
	// }
	stat, err := toFileWriter.Stat()
	println(stat.Size())
}