Constants

A constant holds a value that never changes while the program runs. Constants are declared with the const keyword.

Declaring constants

const pi = 3.14159
const greeting = "Hello"
const maxUsers int = 100

Trying to reassign a constant causes a compile error, which protects values that should stay fixed.

Grouping constants

You can group several constants in one block.

const (
    appName = "LearnGo"
    version = "1.0"
    debug   = false
)

iota

iota is a counter that helps build sequences. It starts at 0 in each const block and increases by one per line.

const (
    Sunday = iota // 0
    Monday        // 1
    Tuesday       // 2
    Wednesday     // 3
)

You can use expressions with iota too:

const (
    _  = iota             // skip 0
    KB = 1 << (10 * iota) // 1024
    MB                    // 1048576
)

fmt.Println(KB, MB)