add: slice internals last lectures

16-slices/10-slice-internals-3-len-cap/2-example/main.go

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+// 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 (
+	s "github.com/inancgumus/prettyslice"
+)
+
+func main() {
+	s.PrintBacking = true
+
+	// ----------------------------------------------------
+	// #1 nil slice
+	var games []string // nil slice
+	s.Show("games", games)
+
+	// ----------------------------------------------------
+	// #2 empty slice
+	games = []string{} // empty slice
+	s.Show("games", games)
+	// s.Show("another empty", []int{})
+
+	// ----------------------------------------------------
+	// #3 non-empty slice
+	games = []string{"pacman", "mario", "tetris", "doom"}
+	s.Show("games", games)
+
+	// ----------------------------------------------------
+	// #4 reset the part using the games slice
+	//    part is empty but its cap is still 4
+	part := games
+	s.Show("part", part)
+
+	part = games[:0]
+	s.Show("part[:0]", part)
+	s.Show("part[:cap]", part[:cap(part)])
+
+	for cap(part) != 0 {
+		part = part[1:cap(part)]
+		s.Show("part", part)
+	}
+
+	// #6 backing array's elements become inaccessible
+	// games = games[len(games):]
+
+	// ----------------------------------------------------
+	// #5 part doesn't have any more capacity
+	//    games slice is still intact
+	s.Show("part", part)
+	s.Show("games", games)
+}