Shulou(Shulou.com)05/31 Report--

This article mainly introduces "how to use map in Go language". In daily operation, I believe many people have doubts about how to use map in GE language. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the doubts about "how to use map in Go language". Next, please follow the editor to study!

Map maps keys to values:

Map must be created with make (not new) before it can be used; a map with a value of nil is empty and cannot be assigned.

The copy code is as follows:

Package mainimport "fmt" type Vertex struct {Lat, Long float64} var map [string] Vertexfunc main () {m = make (map [string] Vertex) m ["Bell Labs"] = Vertex {40.68433, 74.39967,} fmt.Println (m ["Bell Labs"])}

The grammar of map is similar to the structural style grammar, but the key name is required.

Package mainimport "fmt" type Vertex struct {Lat, Long float64} var m = map [string] Vertex {"Bell Labs": Vertex {40.68433,-74.39967,}, "Google": Vertex {37.42202,-122.08408,},} func main () {fmt.Println (m)}

If the top-level type has only the type name, you can omit the key name in the element of the grammar.

Package mainimport "fmt" type Vertex struct {Lat, Long float64} var m = map [string] Vertex {"Bell Labs": {40.68433,-74.39967}, "Google": {37.42202,-122.08408},} func main () {fmt.Println (m)}

Modify map:

Insert or modify an element in map m:

M [key] = elem

Get the element:

The copy code is as follows:

Elem = m [key]

Delete the element:

The copy code is as follows:

Delete (m, key)

Detect the existence of a key by double assignment:

The copy code is as follows:

Elem, ok = m [key]

If key is in m, ok is true. Otherwise, ok is false and elem is the zero value of the element type of map.

Similarly, when a non-existent key is read from map, the result is the zero value of the element type of map.

Package mainimport "fmt" func main () {m: = make (map [string] int) m ["Answer"] = 42 fmt.Println ("The value:", m ["Answer"]) m ["Answer"] = 48 fmt.Println ("The value:", m ["Answer"]) delete (m, "Answer") fmt.Println ("The value:", m ["Answer"]) v Ok: = m ["Answer"] fmt.Println ("The value:", v, "Present?", ok)} so far The study on "how to use map in Go language" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.