Go by Example: 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

Next example: .

by Mark McGranaghan and Eli Bendersky | source | license