A simple example of using functions in Go.

functions.go

package main

import "fmt"

// FUNCTIONS

// specify the argument type(s) and the possible return value type
func sum(x int, y int) int {
	return x + y
}

// Functions with multiple return values
func ageDays(age int) (int, string){
	if age < 0 {
		return 0,"Age cannot be negative"
	} else {
		return 365 * age, ""
	}
}

func main() {
	// Calling the Functions
  
        // SUM
	sumResult := sum(1,2)
	fmt.Println(sumResult) // prints 3
	
        // AGEDAYS
	days, msg := ageDays(25)
	if msg == "" {
		fmt.Print("Age in days:", days)
	} else {
		fmt.Print(msg)
	}
}