Constants

Go supports constants of character, string, boolean, and numeric values.

package main

import (
    "fmt"
    "math"
)
// const declares a constant value.
const s string = "constant"

func main() {
    fmt.Println(s)

    // A const statement can appear anywhere a var statement can
    const n = 500000000

    // Constant expressions perform arithmetic with arbitrary precision
    const d = 3e20 / n
    fmt.Println(d)

    // A numeric constant has no type until it’s given one
    // such as by an explicit conversion.
    fmt.Println(int64(d))

    // A number can be given a type by using it
    // in a context that requires one
    // such as a variable assignment or function call.
    // For example, here math.Sin expects a float64.
    fmt.Println(math.Sin(n))
}

$ go run constant.go
constant
6e+11
600000000000
-0.28470407323754404