学习 Go 语言 0x05：《Go 语言之旅》中映射（map）的练习题代码

* 题目：使用映射（map）实现WordCount

https://tour.go-zh.org/moretypes/23
练习：映射
实现 WordCount。它应当返回一个映射，其中包含字符串 s 中每个“单词”的个数。函数 wc.Test 会对此函数执行一系列测试用例，并输出成功还是失败。

你会发现 strings.Fields 很有帮助。

* 代码

package main

import (
    "golang.org/x/tour/wc"
    "strings"
)

func WordCount(s string) map[string]int {
    
    words := strings.Fields(s)
    m := make(map[string]int)
    for _, word := range words {
    
        n, ok := m[word]
        if ok == false {
    
            m[word] = 1
        } else {
    
            m[word] = n + 1
        }
    }
    return m
}

func main() {
    
    wc.Test(WordCount)
}

运行结果：

$ ./word_count.exe
PASS
 f("I am learning Go!") =
  map[string]int{
    "Go!":1, "I":1, "am":1, "learning":1}
PASS
 f("The quick brown fox jumped over the lazy dog.") =
  map[string]int{
    "The":1, "brown":1, "dog.":1, "fox":1, "jumped":1, "lazy":1, "over":1, "quick":1, "the":1}
PASS
 f("I ate a donut. Then I ate another donut.") =
  map[string]int{
    "I":2, "Then":1, "a":1, "another":1, "ate":2, "donut.":2}
PASS
 f("A man a plan a canal panama.") =
  map[string]int{
    "A":1, "a":2, "canal":1, "man":1, "panama.":1, "plan":1}

对代码做小的改动，运行结果跟上面一样，如下：

package main

import (
    "golang.org/x/tour/wc"
    "strings"
)

func WordCount(s string) map[string]int {
    
    words := strings.Fields(s)
    m := make(map[string]int)
    for _, word := range words {
    
        _, ok := m[word]  // 更改了这里，不再赋给临时变量
        if ok == false {
    
            m[word] = 1
        } else {
    
            m[word]++ // 更改了这里，直接对m[word]的值加1
        }
    }
    return m
}

func main() {
    
    wc.Test(WordCount)
}