go_version.txt

go version go1.13.7 darwin/amd64

output.txt

len=6	cap=6	array ptr: 0xc00000c080	value: [2 3 5 7 11 13]
len=0	cap=6	array ptr: 0xc00000c0c0	value: []
len=4	cap=6	array ptr: 0xc00000c100	value: [2 3 5 7]
len=2	cap=4	array ptr: 0xc00000c140	value: [5 7]

slice-len-cap.go

package main

import (
	"fmt"
	"unsafe"
)

func main() {
	s := []int{2, 3, 5, 7, 11, 13}
	printSlice(s)

	// Slice the slice to give it zero length.
	s = s[:0]
	printSlice(s)

	// Extend its length.
	s = s[:4]
	printSlice(s)

	// Drop its first two values.
	s = s[2:]
	printSlice(s)
}

func printSlice(s []int) {
	fmt.Printf("len=%d\tcap=%d\tarray ptr: %v\tvalue: %v\n", len(s), cap(s), (*unsafe.Pointer)(unsafe.Pointer(&s)), s)
}