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golang

structs

structs are typed collections of fields. They’re useful for grouping data together to form records.

type Person struct {
	GivenName string
	Surname   string
	Age       int
}

Instances of the struct can be created in a variety of ways

var p Person

Above will create a local Person variable that is by default set to zero. For a struct zero means each of the fields is set to their corresponding zero value (0 for ints, 0.0 for floats, “” for strings, nil for pointers, …)

p := new(Person)

Above allocates memory for all the fields, sets each of them to their zero value and returns a pointer *Person. More often we want to give each of the fields a value. We can do this in two ways. Like this:

p := Person{GivenName: "Geoffrey", Surname: "Huntley", Age: 18}

Field names can be left off if you know the order that they are defined

p := Person{"Geoffrey", "Huntley", 18}
var p Person

Structs are mutable

p := Person{GivenName: "Geoffrey", Surname: "Huntley", Age: 18}
p.GivenName = "Geoff"