restructure: arrays and slices

15-project-retro-led-clock/03-animating-the-clock/README.md

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+# GOAL 3: Animate the Clock
+
+## Notes
+
+* Note main.go file contains the solution of the previous step.
+* "solution" folder contains the solution for this step.
+
+## Challenge Steps
+
+1. Create an infinite loop to update the clock
+
+2. Update the clock every second
+
+   [time.Sleep(time.Second)](https://golang.org/pkg/time/#Sleep) will stop the world for 1 second
+
+3. Clear the screen before the infinite loop
+
+   1. Get my library for clearing the screen:
+
+        `go get -u github.com/inancgumus/screen`
+
+   2. Then, import it and call it in your code like this:
+
+        `screen.Clear()`
+
+   3. If you're using Go Playground instead, do this:
+
+        `fmt.Println("\f")`
+
+ 4. Move the cursor to the top-left corner of the screen, before each step
+    of the infinite loop
+
+    * Call this in your code like this:
+
+        `screen.MoveTopLeft()`
+
+    * If you're using Go Playground instead, do this again:
+
+        `fmt.Println("\f")`
+
+---
+
+## SIDE NOTE FOR THE CURIOUS
+
+If you're curious about how my screen clearing package works, read on.
+
+**On bash**, it uses special commands, if you open the code, you can see that.
+
+* `\033` is a special control code:
+* `[2J` clears the screen and the cursor
+* `[H`  moves the cursor to 0, 0 screen position
+* [See for more information](https://bluesock.org/~willkg/dev/ansi.html).
+
+**On Windows**, I'm directly calling the Windows API functions. This is way advanced at this stage of the course, however, I'll probably explain it afterward.
+
+So, my package automatically adjusts itself depending on where it is compiled. On Windows, it uses the special Windows API calls; On other operating systems, it uses the bash special commands that I've explained above.

15-project-retro-led-clock/03-animating-the-clock/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 (
+	"fmt"
+	"time"
+)
+
+func main() {
+	type placeholder [5]string
+
+	zero := placeholder{
+		"███",
+		"█ █",
+		"█ █",
+		"█ █",
+		"███",
+	}
+
+	one := placeholder{
+		"██ ",
+		" █ ",
+		" █ ",
+		" █ ",
+		"███",
+	}
+
+	two := placeholder{
+		"███",
+		"  █",
+		"███",
+		"█  ",
+		"███",
+	}
+
+	three := placeholder{
+		"███",
+		"  █",
+		"███",
+		"  █",
+		"███",
+	}
+
+	four := placeholder{
+		"█ █",
+		"█ █",
+		"███",
+		"  █",
+		"  █",
+	}
+
+	five := placeholder{
+		"███",
+		"█  ",
+		"███",
+		"  █",
+		"███",
+	}
+
+	six := placeholder{
+		"███",
+		"█  ",
+		"███",
+		"█ █",
+		"███",
+	}
+
+	seven := placeholder{
+		"███",
+		"  █",
+		"  █",
+		"  █",
+		"  █",
+	}
+
+	eight := placeholder{
+		"███",
+		"█ █",
+		"███",
+		"█ █",
+		"███",
+	}
+
+	nine := placeholder{
+		"███",
+		"█ █",
+		"███",
+		"  █",
+		"███",
+	}
+
+	colon := placeholder{
+		"   ",
+		" ░ ",
+		"   ",
+		" ░ ",
+		"   ",
+	}
+
+	digits := [...]placeholder{
+		zero, one, two, three, four, five, six, seven, eight, nine,
+	}
+
+	now := time.Now()
+	hour, min, sec := now.Hour(), now.Minute(), now.Second()
+
+	fmt.Printf("hour: %d, min: %d, sec: %d\n", hour, min, sec)
+
+	// [8][5]string
+	clock := [...]placeholder{
+		// extract the digits: 17 becomes, 1 and 7 respectively
+		digits[hour/10], digits[hour%10],
+		colon,
+		digits[min/10], digits[min%10],
+		colon,
+		digits[sec/10], digits[sec%10],
+	}
+
+	for line := range clock[0] {
+		for digit := range clock {
+			fmt.Print(clock[digit][line], "  ")
+		}
+		fmt.Println()
+	}
+}

15-project-retro-led-clock/03-animating-the-clock/solution/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 (
+	"fmt"
+	"time"
+
+	"github.com/inancgumus/screen"
+)
+
+func main() {
+	type placeholder [5]string
+
+	zero := placeholder{
+		"███",
+		"█ █",
+		"█ █",
+		"█ █",
+		"███",
+	}
+
+	one := placeholder{
+		"██ ",
+		" █ ",
+		" █ ",
+		" █ ",
+		"███",
+	}
+
+	two := placeholder{
+		"███",
+		"  █",
+		"███",
+		"█  ",
+		"███",
+	}
+
+	three := placeholder{
+		"███",
+		"  █",
+		"███",
+		"  █",
+		"███",
+	}
+
+	four := placeholder{
+		"█ █",
+		"█ █",
+		"███",
+		"  █",
+		"  █",
+	}
+
+	five := placeholder{
+		"███",
+		"█  ",
+		"███",
+		"  █",
+		"███",
+	}
+
+	six := placeholder{
+		"███",
+		"█  ",
+		"███",
+		"█ █",
+		"███",
+	}
+
+	seven := placeholder{
+		"███",
+		"  █",
+		"  █",
+		"  █",
+		"  █",
+	}
+
+	eight := placeholder{
+		"███",
+		"█ █",
+		"███",
+		"█ █",
+		"███",
+	}
+
+	nine := placeholder{
+		"███",
+		"█ █",
+		"███",
+		"  █",
+		"███",
+	}
+
+	colon := placeholder{
+		"   ",
+		" ░ ",
+		"   ",
+		" ░ ",
+		"   ",
+	}
+
+	digits := [...]placeholder{
+		zero, one, two, three, four, five, six, seven, eight, nine,
+	}
+
+	// For Go Playground, do not use this.
+	screen.Clear()
+
+	// Go Playground will not run an infinite loop.
+	// So, instead, you may loop for 1000 times:
+	// for i := 0; i < 1000; i++ {
+	for {
+		// For Go Playground, use this instead:
+		// fmt.Print("\f")
+		screen.MoveTopLeft()
+
+		now := time.Now()
+		hour, min, sec := now.Hour(), now.Minute(), now.Second()
+
+		clock := [...]placeholder{
+			digits[hour/10], digits[hour%10],
+			colon,
+			digits[min/10], digits[min%10],
+			colon,
+			digits[sec/10], digits[sec%10],
+		}
+
+		for line := range clock[0] {
+			for digit := range clock {
+				fmt.Print(clock[digit][line], "  ")
+			}
+			fmt.Println()
+		}
+
+		// pause for 1 second
+		time.Sleep(time.Second)
+	}
+}