src/puzzlers/article33/q3/demo86.go

package main

import (
	"bufio"
	"bytes"
	"fmt"
	"strings"
)

func main() {
	comment := "Writer implements buffering for an io.Writer object. " +
		"If an error occurs writing to a Writer, " +
		"no more data will be accepted and all subsequent writes, " +
		"and Flush, will return the error. After all data has been written, " +
		"the client should call the Flush method to guarantee all data " +
		"has been forwarded to the underlying io.Writer."
	basicWriter1 := &strings.Builder{}

	size := 300
	fmt.Printf("New a buffered writer with size %d ...\n", size)
	writer1 := bufio.NewWriterSize(basicWriter1, size)
	fmt.Println()

	// 示例1。
	begin, end := 0, 53
	fmt.Printf("Write %d bytes into the writer ...\n", end-begin)
	writer1.WriteString(comment[begin:end])
	fmt.Printf("The number of buffered bytes: %d\n", writer1.Buffered())
	fmt.Printf("The number of unused bytes in the buffer: %d\n",
		writer1.Available())
	fmt.Println("Flush the buffer in the writer ...")
	writer1.Flush()
	fmt.Printf("The number of buffered bytes: %d\n", writer1.Buffered())
	fmt.Printf("The number of unused bytes in the buffer: %d\n",
		writer1.Available())
	fmt.Println()

	// 示例2。
	begin, end = 0, 326
	fmt.Printf("Write %d bytes into the writer ...\n", end-begin)
	writer1.WriteString(comment[begin:end])
	fmt.Printf("The number of buffered bytes: %d\n", writer1.Buffered())
	fmt.Printf("The number of unused bytes in the buffer: %d\n",
		writer1.Available())
	fmt.Println("Flush the buffer in the writer ...")
	writer1.Flush()
	fmt.Println()

	// 示例3。
	basicWriter2 := &bytes.Buffer{}
	fmt.Printf("Reset the writer with a bytes buffer(an implementation of io.ReaderFrom) ...\n")
	writer1.Reset(basicWriter2)
	reader := strings.NewReader(comment)
	fmt.Println("Read data from the reader ...")
	writer1.ReadFrom(reader)
	fmt.Printf("The number of buffered bytes: %d\n", writer1.Buffered())
	fmt.Printf("The number of unused bytes in the buffer: %d\n",
		writer1.Available())
}