常量与iota

package main

import "fmt"

//const 来定义枚举类型
const (
   //可以在const() 添加一个关键字 iota， 每行的iota都会累加1, 第一行的iota的默认值是0
   BEIJING = 10*iota   //iota = 0
   SHANGHAI        //iota = 1
   SHENZHEN          //iota = 2
)

const (
   a, b = iota+1, iota+2 // iota = 0, a = iota + 1, b = iota + 2, a = 1, b = 2
   c, d              // iota = 1, c = iota + 1, d = iota + 2, c = 2, d = 3
   e, f              // iota = 2, e = iota + 1, f = iota + 2, e = 3, f = 4

   g, h = iota * 2, iota *3  // iota = 3, g = iota * 2, h = iota * 3, g = 6, h = 9 
   i, k                  // iota = 4, i = iota * 2, k = iota * 3 , i = 8, k = 12
)

func main() {
   //常量(只读属性)
   const length int = 10

   fmt.Println("length = ", length)

   //length = 100 //常量是不允许修改的。

   fmt.Println("BEIJIGN = ", BEIJING)
   fmt.Println("SHANGHAI = ", SHANGHAI)
   fmt.Println("SHENZHEN = ", SHENZHEN)

   fmt.Println("a = ", a, "b = ", b)
   fmt.Println("c = ", c, "d = ", d)
   fmt.Println("e = ", e, "f = ", f)

   fmt.Println("g = ", g, "h = ", h)
   fmt.Println("i = ", i, "k = ", k)

   // iota 只能够配合const() 一起使用， iota只有在const进行累加效果。
   //var a int = iota 

}