golang 入门(三) 常用数据结构map映射

在python中用于存储kv类型数据的结构是dict字典。golang对应的数据结构就是map映射。

先以python为例

mydict = {}
info_dict = {
    'country': 'china',
}
mydict['name'] = 'hello'
mydict['age'] = 16
mydict['info'] = info_dict
print(mydict)

python test.py
{'name': 'hello', 'age': 16, 'info': {'country': 'china'}}

Process finished with exit code 0

在golang中实现示例

package main

import "fmt"

func main() {
  // 定义一个映射，value类型必须是string
  info := map[string]string{
    "os":      "linux",
    "network": "huawei",
    "program": "golang",
  }

  //定义一个映射，value类型是空接口，放什么数类型都可以。
  m := make(map[string]interface{}, 0)
  m["name"] = "wgw"
  m["country"] = "china"
  m["age"] = 16
  m["info"] = info
  fmt.Println(m)
}

% go run main.go 
map[age:16 country:china info:map[network:huawei os:linux program:golang] name:wgw]

与python的字典相同，遍历map获得k，v的值

for k, v := range m {
        fmt.Printf("key: %v, value: %v \n", k, v)
    }

% go run main.go
key: age, value: 16 
key: info, value: map[network:huawei os:linux program:golang] 
key: name, value: wgw 
key: country, value: china

与python的字典不同，golang从map里获取key对应的value，返回的是两个值

val, ok := m["address"]
  fmt.Println(val, ok)

% go run main.go
# 不存在的val返回值是nil，由于值不存在返回的检索状态就是
<nil> false

删除map中的key

delete(m, "age")
    fmt.Println(m)

% go run main.go
map[country:china info:map[network:huawei os:linux program:golang] name:wgw]

清空map

package main

import "fmt"

func main() {
    info := map[string]string{
        "os":      "linux",
        "network": "huawei",
        "program": "golang",
    }
    
    m := make(map[string]interface{}, 0)
    m["name"] = "wgw"
    m["country"] = "china"
    m["age"] = 16
    m["info"] = info

    // 将已有的map清空
    m = make(map[string]interface{}, 0)
    fmt.Println(m)

}

% go run main.go
map[]

总结：golang中的map使用方式与python中的dict大体相似，重点要记住的就是map["key"] 的返回值是两个。