iota定义常量

iota

//iota作用会自动递增,引用自己定义的表达式。


//定义所有星期,从0到6
package main

import "fmt"

const (
    Sunday = iota    //重点
    Monday
    Tuesday
    Wednesday
    Thursday
    Friday
    Saturday
)

func main() {

    //从第二个开始,自动引用排头兵的表达式,但iota逐一递增.
    fmt.Println(Sunday, Monday, Tuesday) //0 1 2 

}

////定义所有星期,从1到7
package main

import "fmt"

const (
    Monday = iota +1 //0 +1 = 1   //重点
    Tuesday
    Wednesday
    Thursday
    Friday
    Saturday
    Sunday
)

func main() {

    //从第二个开始,自动引用排头兵的表达式,但iota逐一递增.
    fmt.Println(Monday, Tuesday) //1 2

}

//定义5大常任理事国编号100-500

package main

import "fmt"

const (
    USA = (iota + 1) * 100  //重点
    China
    Russia
    Britain
    France
)

func main() {

    fmt.Println(USA, China, Russia, Britain, France) //100 200 300 400 500

}