A struct is a collection of fields. Struct fields are accessed using a dot.
Example
package main
import "fmt"
type Vertex struct {
X int
Y int
}
func main() {
fmt.Println(Vertex{1, 2})
v := Vertex{1, 2}
v.X = 4
fmt.Println(v.X)
}
{1 2}
4
Pointers to Structs
Struct fields can also be accessed using a struct pointer.
package main
import "fmt"
type Vertex struct {
X int
Y int
}
func main() {
v := Vertex{1, 2}
p := &v // struct pointer p
p.X = 1e9
// (*p).X = 9 // output would be {9 2}
fmt.Println(v)
}
{1000000000 2}
We could write (*p).X to access the field X of the Vertex struct. However, this is a cumbersome notation. So, Go allows us to use p.X without this explicit derefence.
Struct Literals
A struct literal denotes a newly allocated struct value by listing the values of its fields. The predix & returns a pointer to the struct value.
package main
import "fmt"
type Vertex struct {
X, Y int
}
var (
v1 = Vertex{1, 2}
v2 = Vertex{X: 1} // using Name: syntax; Y: 0 is implicit
v3 = Vertex{} // X:0 and Y:0
p = &Vertex{1, 2} // has type *Vertex
)
func main() {
fmt.Println(v1, v2, v3, p)
}
