Constant

const

package main

import "fmt"

const pi = 3.1415
const e = 2.7

func main() {
    // e = 2.8 // 常量不能修改
    fmt.Println(pi, e)
}

iota

package main

import "fmt"

const (
    Spring = iota // 0
    Summer        // 1
    Autumn        // 2
    Winter        // 3
)

func main() {
    fmt.Println(Spring, Summer, Autumn, Winter)

    const (
        n1 = iota // 0
        n2        // 1
        n3 = 100
        n4 = iota // 3
    )
    const n5 = iota // 0
    fmt.Println(n1, n2, n3, n4, n5)
}