file copy

File copy, written without buffering and buffered respectively.

// file_io project main.go
/*
package main

import (
	"fmt"
	"log"
	"os"
)

func main() {
	fmt.Println("Hello World!")
	file, err := os.Open("E:/go_data/test.py")
	if err != nil {
		fmt.Printf("open test.py err.\n")
		log.Fatal(err)
	}

	file_out, err := os.Create("e:/go_data/test2.py")
	if err != nil {
		fmt.Printf("open test2.py err.\n")
		log.Fatal(err)
	}

	data := make([]byte, 100)
	var count int
	var n int
	for {
		count, err = file.Read(data)
		fmt.Printf("count=%v\n", count)
		if err != nil {
			break
		}
		n, err = file_out.Write(data[0:count])
		fmt.Printf("n=%v\n", n)
		if err != nil {
			break
		}
	}
	file.Close()
	file_out.Close()
}
*/

/*
package main

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

func main() {
	fmt.Println("Hello World!")
	file, err := os.Open("E:/go_data/test.py")
	if err != nil {
		fmt.Printf("open test.py err.\n")
		log.Fatal(err)
	}

	file_out, err := os.Create("e:/go_data/test2.py")
	if err != nil {
		fmt.Printf("open test2.py err.\n")
		log.Fatal(err)
	}

	data := make([]byte, 100)
	var count int
	var n int
	var reader *bufio.Reader
	var writer *bufio.Writer

	reader = bufio.NewReaderSize(file, 1024)
	writer = bufio.NewWriterSize(file_out, 1024)

	for {

		count, err = reader.Read(data)
		fmt.Printf("count=%v\n", count)
		if err != nil {
			fmt.Printf("err=%v\n", err)
			break
		}

		n, err = writer.Write(data[0:count])
		fmt.Printf("n=%v\n", n)
		if err != nil {
			fmt.Printf("err=%v\n", err)
			break
		}

	}

	writer.Flush()
	file.Close()
	file_out.Close()
}
*/

package main

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

func main() {
	fmt.Println("Hello World!")
	file, err := os.Open("E:/go_data/test.py")
	if err != nil {
		fmt.Printf("open test.py err.\n")
		log.Fatal(err)
	}

	file_out, err := os.Create("e:/go_data/test2.py")
	if err != nil {
		fmt.Printf("open test2.py err.\n")
		log.Fatal(err)
	}

	var reader *bufio.Reader
	var writer *bufio.Writer

	reader = bufio.NewReaderSize(file, 1024)
	writer = bufio.NewWriterSize(file_out, 1024)

	reader.WriteTo(writer)
	writer.Flush()
	file.Close()
	file_out.Close()
}