go basic

package main

import (
	"fmt"
	"math/rand"
	"time"
)

func main() {
	rand.Seed(time.Now().Unix())
	fmt.Println("My favorite number is :", rand.Int()%20)
}

package main

import (
	"fmt"
	"runtime"
)

func main() {
	fmt.Println("Go runs on")
	switch os := runtime.GOOS; os {
	case "darwin":
		fmt.Println("os x")
	case "linux":
		fmt.Println("Linux.")
	default:
		fmt.Println("windows")
	}
}

package main

import (
	"fmt"
	// "reflect"
)

func printSlice(s string, x []int) {
	fmt.Printf("%s len=%d cap=%d %v\n", s, len(x), cap(x), x)
}
func main() {
	var a []int
	printSlice("a", a)

	//append works on nil slice
	a = append(a, 0)
	printSlice("a", a)

	a = append(a, 2, 3, 4)
	printSlice("a", a)

}