Go编程之基础数据类型Map

Golang之Map

一、创建和赋值

m := map[string]int{"one", 1, "tow": 2, "three": 3}
m1 := map[string]int{}
m1["one"] = 1
m2 := make(map[string]int, 10)

maps := make(map[string]string)

maps["one"] = "zhangsan"
maps["two"] = "tom"
maps["three"] = "mary"

for v, k := range maps{
    fmt.Println(k, v)
}

二、删除

func TestMap(t *testing.T) {
  item := map[int]string{
    1: "12345",
    2: "world",
    3: "long",
  }

  t.Log(item)

  delete(item, 1)

  t.Log(item)

}

三、修改

func TestUpdate(t *testing.T) {
  item := map[int]string{
    1: "12345",
    2: "world",
    3: "long",
  }
  t.Log(item)
  item[1] = "hello"
  t.Log(item)

}

type Student struct {
  Id int
  Name string
}

func TestObj(t *testing.T) {

  data := make(map[int]*Student)
  data[1] = &Student{
    Id: 1,
    Name: "tom",
  }

  data[2] = &Student{
    Id: 2,
    Name: "zs",
  }

  t.Log(data[1])
  t.Log(data[2])

  one := data[1]
  one.Name = "asas"

  t.Log(data[1])
  t.Log(data[2])

}

四、map排序

func TestMapSort(t *testing.T) {
  items := map[string]int{
    "Java": 1,
    "Python": 2,
    "C++": 3,
    "C#": 4,
    "PHP": 5,
    "JavaScript": 6,
  }

  var SortString []string
  for k := range items {
    SortString = append(SortString, k)
  }

  sort.Strings(SortString)

  for _, k := range SortString {
    fmt.Println("key:", k, "Value:", items[k])
  }

}

五、map嵌套

type EmployeeInformation map[string]int

func TestMapNested(t *testing.T) {
  items := make(map[string]EmployeeInformation)
  EmployeeItem := make(EmployeeInformation)
  EmployeeItem["beijing"] = 1
  EmployeeItem["tianjin"] = 2
  EmployeeItem["hebei"] = 3

  items["address1"] = EmployeeItem
  items["address2"] = EmployeeInformation{
    "shandong": 11,
    "fuzhou": 23,
  }

  t.Log(items)
}

func TestCitys(t *testing.T) {
  // 省
  province := make(map[string]map[string][]string)
  // 市
  city := make(map[string][]string)
  // 景区
  scenery := make(map[string][]string)

  scenery["西安"] = []string{"秦始皇兵马俑","大雁塔","大唐芙蓉园","华清池","黄巢堡国家森林公园","西安碑林博物馆"}
  scenery["安康"] = []string{"中坝大峡谷","香溪洞","安康双龙生态旅游度假区"}

  city["西安市区"] = []string{"新城区","碑林区","莲湖区","灞桥区","未央区","雁塔区","阎良区","临潼区","长安区","高陵区","咸阳区"}
  city["安康市区"] = []string{"汉滨区","汉阴县","石泉县","宁陕县","紫阳县","岚皋县","平利县"}

  province["陕西省"] = city

  city["西安景区"] = scenery["西安"]
  city["安康景区"] = scenery["安康"]

  for k, v := range province {
    fmt.Println(k, v)
    for x, y := range v {
      fmt.Println(x, y)
    }
  }

}

六、make和new

• make 只能为 slice、map或 channel 类型分配内存并初始化，同时返回一个有初始值的 slice、map 或 channel 类型引用，不是指针。
• 内建函数 new 用来分配内存，它的第一个参数是一个类型，不是一个值，它的返回值是一个指向新分配类型零值的指针。