Golang : On enumeration
In Golang, it is fairly simple to declare enumeration. Just group the similar items into a const
group and use the iota
keyword.
For example, to declares constants :
const Monday = 1
const Tuesday = 2
Enumeration is formed by putting constants into parentheses. For example :
const (
Monday = 1
Tuesday = 2
Wednesday = 3
)
Golang has one keyword iota
that make the consts into enum.
const (
Monday = iota
Tuesday
Wednesday
)
and let say you want to explicit declare the constants type. You can do something like :
type Day int
const (
Monday Day = iota
Tuesday
Wednesday
)
and this code will test out the enumeration :
package main
import (
"fmt"
)
type Day int
const (
Monday Day = iota // starts from 0
Tuesday
Wednesday
Thursday
Friday
)
func main() {
fmt.Println(Monday) // should return 0
fmt.Println(Friday) // should print 4
}
Output :
0
4
add a variable and a method to print out the string value instead of iota.
// [...] is to tell the Go intrepreter/compiler to figure out the array size
var days = [...]string {"Monday","Tuesday","Wednesday","Thursday","Friday",}
func (day Day) String() string {
return days[day]
}
and the codes below will printout the enumeration in string.
package main
import (
"fmt"
)
type Day int
const (
Monday Day = iota // starts from 0
Tuesday
Wednesday
Thursday
Friday
)
// [...] is to tell the Go intrepreter/compiler to figure out the array size
var days = [...]string {"Monday","Tuesday","Wednesday","Thursday","Friday",}
func (day Day) String() string {
return days[day]
}
func main() {
fmt.Println(Monday) // should return Monday
fmt.Println(Friday) // should print Friday
}
Output :
Monday
Friday
By Adam Ng
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