The constant generator iota golang

Constant declaration can be used to initialize iota constant generator, which is used to generate a set of constants to initialize a similar rule, but do not write it again each line initialization expression. In a const declaration statement, in the first line of the constant declaration where, the IOTA will be set to 0 , then add a line in each of a constant declaration.

 

The following are examples of the package from the time it first defines a Weekday named type, and defines a constant for the day of the week, Sunday from 0 starts. In other programming languages, this type generally referred to as an enumerated type.

 

type Weekday int
const (
　　Sunday Weekday = iota
　　Monday
　　Tuesday
　　Wednesday
　　Thursday
　　Friday
　　Saturday
)

 

Sunday will correspond to 0, Monday is 1, and so on.

 

We can also use the complex constant expressions iota, following from net example package for a minimum of an unsigned integer 5bit each bit specify a name:

 

type Flags uint
const (
    FlagUp Flags = 1 << iota // is up
    FlagBroadcast // supports broadcast access capability
    FlagLoopback // is a loopback interface
    FlagPointToPoint // belongs to a point-to-point link
    FlagMulticast // supports multicast access capability
)

 

With increasing iota, each corresponding to a constant expression . 1 << iota , continuous two powers, one for each bit position. Using these constants can be used for testing, set or clear the corresponding bit value of the bit