常量总结

package main

import (
    "fmt"
)

const PI = 3.1415926

func main() {
    fmt.Println("Hello! Go World! this is constant")
    fmt.Println(PI)
    // 常量可以省略类型
    const A string = "AAA"
    const B = "BBB"
    fmt.Println(A)
    fmt.Println(B)
    // 常量的值必须是能够在编译时就能够确定的
    const MYNAME = "Tacks" + "is so cool"
    // 内置函数 在编译期间就能获得
    const MYNAMELEN int = len(MYNAME)
    fmt.Println(MYNAME, MYNAMELEN)

    // 并行赋值
    const Mon, Tue, Wed = 1, 2, 3
    fmt.Println(Mon, Tue, Wed)

    // 枚举
    const (
        UnKnown = 0
        Female  = 1
        Male    = 2
    )
    fmt.Println(UnKnown, Female, Male)

    // 借助 iota
    const (
        // 每当 iota 在新的一行被使用时，它的值都会自动加 1
        Sunday = iota
        Monday
        Tuesday
        Wednesday
        Thursday
        Friday
        Saturday
    )
    fmt.Println(Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday)

}