Go String after variable declaration

Question

Take a look at this snip found at here

import (
 "encoding/xml"
 "fmt"
 "os"
)
func main() {
 type Address struct {
 City, State string
 }
 type Person struct {
 XMLName xml.Name `xml:"person"`
 Id int `xml:"id,attr"`
 FirstName string `xml:"name>first"`
 LastName string `xml:"name>last"`
 Age int `xml:"age"`
 Height float32 `xml:"height,omitempty"`
 Married bool
 Address
 Comment string `xml:",comment"`
 }
 v := &Person{Id: 13, FirstName: "John", LastName: "Doe", Age: 42}
 v.Comment = " Need more details. "
 v.Address = Address{"Hanga Roa", "Easter Island"}
 enc := xml.NewEncoder(os.Stdout)
 enc.Indent(" ", " ")
 if err := enc.Encode(v); err != nil {
 fmt.Printf("error: %v\n", err)
 }
}

I can understand in the struct Person, It has a var called Id, which is of type int, but what about the stuff

xml:"person" 

after int? What does it mean? Thanks.

Answer 1

It's a struct tag. Libraries use these to annotate struct fields with extra information; in this case, the module encoding/xml uses these struct tags to denote which tags correspond to the struct fields.

• Roland Illig: See go.dev/ref/spec#Struct_types for the primary source.

Answer 2

which mean that variable will present in the name of Person example

type sample struct {
 dateofbirth string `xml:"dob"`
}
In the above example, the field 'dateofbirth' will present in the name of 'dob' in the XML.

you will see this notation often in go struct.