package main

import (
   "fmt"
)

func main() {
   fmt.Println("Inside the main function")

   arr := [3]int{1,2,3}

   fmt.Println("The length of the array is:", len(arr))
}

Inside the main function
The length of the array is: 3

package main

import (
   "fmt"
)

func main() {
   sl := []int{2, 3, 5, 7, 10, 15}
   check(sl)

   sl = sl[2:]
   check(sl)

   sl = sl[:0]
   check(sl)
}

func check(sl []int) {
   fmt.Printf("len=%d cap=%d %v\n", len(sl), cap(sl), sl)
}

len=6 cap=6 [2 3 5 7 10 15]
len=4 cap=4 [5 7 10 15]
len=0 cap=4 []