Constants
suggest changeGo supports constants of character, string, boolean, and numeric values.
Constant basics:
// Greeting is an exported (public) string constant
const Greeting string = "Hello World"
// we can group const declarations
const (
// years is an unexported (package private) int constant
years int = 10
truth bool = true
)
Constants can be used like variables, except that their value can't change.
An example:
// collection: Essential Go
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
}
constant
10
n=10 is of type int
4.3
-0.5440211108893699
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