func main() {
    const a string = "smallming"
    const b = 123
    const c = 3*2 + 5//不要指定类型
    const d = 1.5//不要指定类型

    fmt.Printf("%T %T",c,d)//int float

    fmt.Println(c+d)//12.5

    //下面这种方式是错误的
    i := 3
    const e = i*2 + 5 //const initializer i * 2 + 5 is not a constant
}

const (
        a = 1
        b = 2
        c = true
    )

func main() {
    const (
        a = 1
        b
        c
    )
    fmt.Println(a,b,c)//输出:1 1 1
}

func main() {
    const (
        a = iota
        b 
        c 
    )
    fmt.Println(a, b, c) //输出: 0 1 2

    const (
        d = iota << 1
        e 
        f 
    )
    fmt.Println(d, e, f) //输出:0 2 4
}

func main() {
    const (
        a = 5    //iota=0
        b = 3    //iota=1
        c = iota //iota=2
        d        //iota=3
    )
    fmt.Println(a, b, c, d) //输出5 3 2 3

    const (
        e = iota //iota=0
        f        //iota=1
        g = 10   //iota=2
        h        //iota=3
        i = iota //iota=4
        j        //iota=5
    )
    fmt.Println(e, f, g, h, i, j) // 0 1 10 10 4 5
}