Create, open, read and write string to file.

create_open_read_write_file.go

package main

import (
	"bufio"
	"fmt"
	"os"
)

const file_path string = "output.txt"

var scanner *bufio.Scanner = bufio.NewScanner(os.Stdin)

//var writer *bufio.Writer = bufio.NewWriter(os.Stdout)

func main() {
	create_write("dfdf")
	open_write(" update!!!")
	fmt.Print(open_read())
}

func create_write(data string) {
	if data == "" {
		fmt.Print("error! nothing to write!")
		return
	}
	fo, err := os.Create(file_path)
	if err != nil {
		fmt.Print("error! create file failed!")
		return
	}
	writer := bufio.NewWriter(fo)
	defer fo.Close()
	defer writer.Flush()
	writer.WriteString(data)
}

func open_write(data string) {
	if data == "" {
		fmt.Print("error! nothing to write!")
		return
	}
	foi, err := os.OpenFile(file_path, os.O_APPEND|os.O_WRONLY, os.ModePerm)
	if err != nil {
		fmt.Print("error! open file failed!")
		return
	}
	writer := bufio.NewWriter(foi)
	defer foi.Close()
	defer writer.Flush()
	writer.WriteString(data)
}

func open_read() string {
	fi, err := os.Open(file_path)
	if err != nil {
		fmt.Print("error! open file failed!")
		return ""
	}
	scanner := bufio.NewScanner(fi)
	defer fi.Close()
	scanner.Scan()
	return scanner.Text()
}