Example
Constants are declared like variables, but using the const keyword:
const Greeting string = "Hello World"
const Years int = 10
const Truth bool = true
Like for variables, names starting with an upper case letter are exported (public), names starting with lower case are not.
// not exported
const alpha string = "Alpha"
// exported
const Beta string = "Beta"
Constants can be used like any other variable, except for the fact that the value cannot be changed. Here's an example:
package main
import (
"fmt"
"math"
)
const s string = "constant"
func main() {
fmt.Println(s) // constant
// A `const` statement can appear anywhere a `var` statement can.
const n = 10
fmt.Println(n) // 10
fmt.Printf("n=%d is of type %T\n", n, n) // n=10 is of type int
const m float64 = 4.3
fmt.Println(m) // 4.3
// An untyped constant takes the type needed by its context.
// For example, here `math.Sin` expects a `float64`.
const x = 10
fmt.Println(math.Sin(x)) // -0.5440211108893699
}
