add: slice internals backing array and slice header

16-slices/09-slice-internals-2-slice-header/1-theory/main.go

@@ -0,0 +1,46 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"fmt"
+
+	s "github.com/inancgumus/prettyslice"
+)
+
+func main() {
+	//
+	// each int element is 4 bytes (on 64-bit)
+	//
+	// let's say the ages point to 1000th.
+	// ages[1:] will point to 1004th
+	// ages[2:] will point to 1008th and so on.
+	//
+	// they all will be looking at the same
+	// backing array.
+	//
+
+	ages := []int{35, 15, 25}
+	red, green := ages[0:1], ages[1:3]
+
+	s.Show("ages", ages)
+	s.Show("red", red)
+	s.Show("green", green)
+
+	fmt.Println(red[0])
+	// fmt.Println(red[1]) // error
+	// fmt.Println(red[2]) // error
+
+	{
+		var ages []int
+		s.Show("nil slice", ages)
+
+		// or just:
+		s.Show("nil slice", []int(nil))
+	}
+}