bufio-buffer-strings-scanner 处理输入并高效拼接

• 关于使用 bufio.Scanner 读取数据
• 字符串拼接如何最快-gocn
• 字符串拼接详细比较-reddit

参考结论 单次调用性能：操作符+>strings.Join>=bytes.Buffer>fmt.Sprintf 灵活性：bytes.Buffer>fmt.Sprintf>=strings.Join>操作符+

package main
import (
    "bufio"
    "bytes"
    "fmt"
    "os"
    "strings"
)
func scanandreadandjoin() {
    input := "foo bar baz" // or os.Stdin
    var buf bytes.Buffer
    scanner := bufio.NewScanner(strings.NewReader(input))
    scanner.Split(bufio.ScanWords)
    for scanner.Scan() {
        fmt.Println(scanner.Bytes())
        buf.Write(scanner.Bytes())
    }
    output := buf.Bytes()
    fmt.Println(output, output[0])
}
func main() {
    var buf bytes.Buffer
    scanner := bufio.NewScanner(os.Stdin)
    scanner.Split(bufio.ScanWords)
    for scanner.Scan() {
        fmt.Println(scanner.Bytes())
        buf.Write(scanner.Bytes())
    }
    output := buf.Bytes()
    fmt.Println(output, output[0])
    // scanandreadandjoin()
}