Go程序设计语言练习题（7.1-7.10）

7.1：使用类似ByteCounter的想法，实现单词和行的计数器，实现时考虑使用bufio.ScanWords。

package main

import (
    "bufio"
    "fmt"
)

type WordsCounter int

func (c *WordsCounter) Write(content []byte) (int, error) {
    for start := 0; start < len(content); {
        //跳过开头的space,返回遇到第一个word后下次scan的开始index
        //Hello Worlds 调用bufio.ScanWords返回
        //6 [Hello的字节slice] nil
        advance, _, err := bufio.ScanWords(content[start:], true)
        if err != nil {
            return 0, err
        }
        start += advance
        (*c)++
    }
    return int(*c), nil
}

type LinesCounter int

func (c *LinesCounter) Write(content []byte) (int, error) {
    for start := 0; start < len(content); {
        advance, _, err := bufio.ScanLines(content[start:], true)
        if err != nil {
            return 0, err
        }
        start += advance
        (*c)++
    }
    return int(*c), nil
}

func main() {
    var wc WordsCounter
    wc.Write([]byte("Hello Worlds Test Me"))
    fmt.Println(wc) // 4
    wc.Write([]byte("append something to the end"))
    fmt.Println(wc) // 9

    var lc LinesCounter
    fmt.Fprintf(&lc, "%s\n%s\n%s\n", "Hello World", "Second Line", "Third Line")
    fmt.Println(lc) // 3
    fmt.Fprintf(&lc, "%s\n%s\n%s", "第4行", "第5行", "")
    fmt.Println(lc) // 5
}

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