在go語言中iota比較特殊，是一個被編譯器修改的常量，在每一個const關鍵字出現時被重置為0，然後在下一個const出現之前，每出現一次iota，其所代表的數字就會自動加1

左移運算子”<<”是雙目運算子。左移n位就是乘以2的n次方。 其功能把”<<”左邊的運算數的各二進位全部左移若干位，由”<<”右邊的數指定移動的位數，高位丟棄，低位補0。

右移運算子”>>”是雙目運算子。右移n位就是除以2的n次方。 其功能是把”>>”左邊的運算數的各二進位全部右移若干位，”>>”右邊的數指定移動的位數。

package iota
 


import "fmt"

func Test()  {

    const(
        c1 = iota  //c1=0
        c2 = iota  //c2=1
        c3 = iota  //c3=2
    )

    fmt.Println("c1 = ",c1," c2 = ",c2," c3 = ",c3,"\n")

    const(
        a = 1 << iota //a = 1
        b = 1 << iota //b = 2
        c = 1 << iota //c = 4
    )
    fmt.Println("a = "
 
,a," b = ",b," c = ",c,"\n")

    const(
        v1 = iota //v1 = 0
        v2        //v2 = 1
        v3        //v3 = 2
    )
    fmt.Println("v1 = ",v1," v2 = ",v2," v3 = ",v3,"\n")

    const(
        x = 1 <<iota //x = 1
        y             //y = 2
        z             //z = 4
    )
    fmt.Println("x = "
 
,x," y = ",y," z = ",z)
}

程式碼執行結果和上面註釋相同：