move: structs to root

24-structs/03-compare-assign/main.go

@@ -0,0 +1,94 @@
+// 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"
+
+// #1b: create the song struct type
+type song struct {
+	title, artist string
+}
+
+// #5: structs can contain other structs
+type playlist struct {
+	genre string
+
+	// songTitles []string
+	// songArtist []string
+
+	// #6: include a slice of song structs
+	songs []song
+}
+
+func main() {
+	// #1: create two struct values with the same type
+	song1 := song{title: "wonderwall", artist: "oasis"}
+	song2 := song{title: "super sonic", artist: "oasis"}
+
+	fmt.Printf("song1: %+v\nsong2: %+v\n", song1, song2)
+
+	// #4: structs are copied
+	// song1 = song2
+
+	// #3: structs can be compared
+	if song1 == song2 {
+		// #2: struct comparison works like this
+		// if song1.title == song2.title &&
+		// 	song1.artist == song2.artist {
+		fmt.Println("songs are equal.")
+	} else {
+		fmt.Println("songs are not equal.")
+	}
+
+	// #8
+	songs := []song{
+		// #7b: you don't have to type the element types
+		{title: "wonderwall", artist: "oasis"},
+		{title: "radioactive", artist: "imagine dragons"},
+	}
+
+	// #7: a struct can include another struct
+	rock := playlist{
+		genre: "indie rock",
+		songs: songs,
+	}
+
+	// #9: you can't compare struct values that contains incomparable fields
+	// you need to compare them manually
+
+	// clone := rock
+	// if rock.songs == clone {
+	// }
+	// if songs == songs {
+
+	// #11: song is a clone, it cannot change the original struct value
+	song := rock.songs[0]
+	song.title = "live forever"
+
+	// #11c: directly set the original one
+	rock.songs[0].title = "live forever"
+
+	// #11b
+	fmt.Printf("\n%+v\n%+v\n", song, rock.songs[0])
+
+	// #10: printing
+	fmt.Printf("\n%-20s %20s\n", "TITLE", "ARTIST")
+	for _, s := range rock.songs {
+		// s := rock.songs[i]
+
+		// #12b: s is a copy inside because struct values are copied
+		s.title = "destroy"
+		fmt.Printf("%-20s %20s\n", s.title, s.artist)
+	}
+
+	// #12
+	fmt.Printf("\n%-20s %20s\n", "TITLE", "ARTIST")
+	for _, s := range rock.songs {
+		fmt.Printf("%-20s %20s\n", s.title, s.artist)
+	}
+}