Structs and Maps

Defining

package main

import (
 "fmt"
)

type Vertex struct {
 X int
 Y int
}

func main() {
 v := Vertex{1, 2}
 v.X = 4
 fmt.Println(v.X, v.Y) // => 4 2
}

See: Structs

Literals

v := Vertex{X: 1, Y: 2}
// Field names can be omitted
v := Vertex{1, 2}
// Y is implicit
v := Vertex{X: 1}

You can also put field names.

Maps

m := make(map[string]int)
m["k1"] = 7
m["k2"] = 13
fmt.Println(m) // => map[k1:7 k2:13]

v1 := m["k1"]
fmt.Println(v1)     // => 7
fmt.Println(len(m)) // => 2

delete(m, "k2")
fmt.Println(m) // => map[k1:7]

_, prs := m["k2"]
fmt.Println(prs) // => false

n := map[string]int{"foo": 1, "bar": 2}
fmt.Println(n) // => map[bar:2 foo:1]

Pointers to structs

v := &Vertex{1, 2}
v.X = 2

Doing v.X is the same as doing (*v).X, when v is a pointer.

Comments