go by example part 2

5-go-by-example/18-structs.go

@@ -0,0 +1,49 @@
+package main
+
+import "fmt"
+
+// Go’s structs are typed collections of fields. They’re useful for grouping data together to form records.
+
+// this person struct type has name and age fields
+type person struct {
+	name string
+	age  int
+}
+
+// newPerson constructs a new person struct with the given name
+// safely return a pointer to local variable as a local variable will survive the scope of the function
+func newPerson(name string) *person {
+	p := person{name: name}
+	p.age = 42
+	return &p
+}
+
+func main() {
+	// create a new struct
+	fmt.Println(person{"Bob", 20})
+
+	// name the fields when initializing a struct
+	fmt.Println(person{name: "Alice", age: 30})
+
+	// omitted fields will be zero-valued
+	fmt.Println(person{name: "Fred"})
+
+	// & prefix yields a pointer to the struct
+	fmt.Println(&person{name: "Ann", age: 40})
+
+	// encapsulate new struct creation in constructor functions (ideomatic)
+	fmt.Println(newPerson("Jon"))
+
+	// access struct fields with a dot
+	s := person{name: "Sean", age: 50}
+	fmt.Println(s.name)
+
+	// use dots with struct pointers
+	// the pointers are automatically dereferenced
+	sp := &s
+	fmt.Println(sp.age)
+
+	// structs are mutable
+	sp.age = 51
+	fmt.Println(sp.age)
+}