概念
Golang一種內(nèi)置結(jié)構(gòu)，形式<key,value>，類似Java中的HashMap或者Python中的dict（字典）。其中key是可比較的，不能為slice，因?yàn)閟lice沒(méi)有實(shí)現(xiàn)比較操作。另外需要注意一點(diǎn)就是map是引用類型，作為參數(shù)存在副作用。
操作以及例子
如何創(chuàng)建
使用make,語(yǔ)法格式：make(map[key-type]val-type)
可以在聲明的時(shí)候初始化：map[key-type]val-type{key:value, ...}
如何修改
賦值：name[key]=val
刪除: delete(name, key)
如何訪問(wèn)
直接使用下標(biāo):name[key]
帶有校驗(yàn)型: val, ok := name[key], ok是false表示key對(duì)應(yīng)的值不存在
例子：
// Maps are Go's built-in associative data type(sometimes called hashes or dicts in other languages)
package main
import "fmt"
func main() {
? // to create an empty map, use the builtin make: make(map[key-type]val-type)
? m := make(map[string]int)
? // set key/value pairs using typical name[key]=val syntax
? m["k1"] = 7
? m["k2"] = 13
? // Printing a map with e.g. fmt.Println will show all of its key/value pairs.
? fmt.Println("map:", m)
? // Get a value for a key with name[key]
? v1 := m["k1"]
? fmt.Println("v1:", v1)
? // the builtin le returns the numbers of key/value pairs when called on a map
? fmt.Println("len:", len(m))
? // the builtin delete removes key/value pairs from a map
? delete(m, "k2")
? fmt.Println("map:", m)
? /**
? * the optional second return value when getting a value from a map
? * indicates if the key was present in the map. This can be used to dismbiguate between missing keys
? * and keys with zero values like 0 or "". Here we didn't need the value itself, so we ignored it with
? * the blank identifer _.
? **/
? _, prs := m["k2"]
? fmt.Println("prs:", prs)
? if !prs {
? ? fmt.Println("m[\"k2\"] is not exist.")
? }
? // you can also decalre and initialize a new map in the same line with this syntax
? n := map[string]int{"foo": 1, "bar": 2}
? fmt.Println("map:", n)
}
參考資料
https://golang.google.cn/doc/effective_go.html#maps
https://gobyexample.com/maps
