restructure: arrays and slices

15-project-retro-led-clock/01-printing-the-digits/solution/main.go

@@ -0,0 +1,126 @@
+// 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"
+)
+
+func main() {
+	// for keeping things easy to read and type-safe
+	type placeholder [5]string
+
+	zero := placeholder{
+		"███",
+		"█ █",
+		"█ █",
+		"█ █",
+		"███",
+	}
+
+	one := placeholder{
+		"██ ",
+		" █ ",
+		" █ ",
+		" █ ",
+		"███",
+	}
+
+	two := placeholder{
+		"███",
+		"  █",
+		"███",
+		"█  ",
+		"███",
+	}
+
+	three := placeholder{
+		"███",
+		"  █",
+		"███",
+		"  █",
+		"███",
+	}
+
+	four := placeholder{
+		"█ █",
+		"█ █",
+		"███",
+		"  █",
+		"  █",
+	}
+
+	five := placeholder{
+		"███",
+		"█  ",
+		"███",
+		"  █",
+		"███",
+	}
+
+	six := placeholder{
+		"███",
+		"█  ",
+		"███",
+		"█ █",
+		"███",
+	}
+
+	seven := placeholder{
+		"███",
+		"  █",
+		"  █",
+		"  █",
+		"  █",
+	}
+
+	eight := placeholder{
+		"███",
+		"█ █",
+		"███",
+		"█ █",
+		"███",
+	}
+
+	nine := placeholder{
+		"███",
+		"█ █",
+		"███",
+		"  █",
+		"███",
+	}
+
+	// This array's type is "like": [10][5]string
+	//
+	// However:
+	// + "placeholder" is not equal to [5]string in type-wise.
+	// + Because: "placeholder" is a defined type, which is different
+	//   from [5]string type.
+	// + [5]string is an unnamed type.
+	// + placeholder is a named type.
+	// + The underlying type of [5]string and placeholder is the same:
+	//     [5]string
+	digits := [...]placeholder{
+		zero, one, two, three, four, five, six, seven, eight, nine,
+	}
+
+	// Explanation: digits[0]
+	// + Each element of clock has the same length.
+	// + So: Getting the length of only one element is OK.
+	// + This could be: "zero" or "one" and so on... Instead of: digits[0]
+	//
+	// The range clause below is ~equal to the following code:
+	// line := 0; line < 5; line++
+	for line := range digits[0] {
+		// Print a line for each placeholder in digits
+		for digit := range digits {
+			fmt.Print(digits[digit][line], "  ")
+		}
+		fmt.Println()
+	}
+}