add: unfinished code. people are having problems

14-arrays/_experimental/wall-clock/main.go

@@ -0,0 +1,191 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+// NOTE: We're going to refactor this code in the functions section.
+
+const (
+	charDefault   = "█"
+	charColon     = "░"
+	charEmpty     = " "
+	charSeparator = "  "
+
+	// clears the screen
+	//
+	// only works on bash command prompts
+	// \033 is a control code: [2J clears the screen
+	//
+	// For Go Playground, use: "\f"
+	charClear = "\033[H\033[2J"
+)
+
+func main() {
+	// for keeping things easy to read and type-safe
+	type placeholder [5][3]byte
+
+	// we're using arrays because:
+	// - the pattern of a placeholder is constant (it doesn't change)
+	// - the placeholders in the clock is constant (which is 8)
+	//
+	// so, whenever values are precomputed or constant, use an array.
+	//
+	// you can always convert it to a slice easily. you'll learn
+	// how to do so in the slices section.
+	digits := [10]placeholder{
+		// 0
+		{
+			{1, 1, 1},
+			{1, 0, 1},
+			{1, 0, 1},
+			{1, 0, 1},
+			{1, 1, 1},
+		},
+
+		// 1
+		{
+			{1, 1, 0},
+			{0, 1, 0},
+			{0, 1, 0},
+			{0, 1, 0},
+			{1, 1, 1},
+		},
+
+		// 2
+		{
+			{1, 1, 1},
+			{0, 0, 1},
+			{1, 1, 1},
+			{1, 0, 0},
+			{1, 1, 1},
+		},
+
+		// 3
+		{
+			{1, 1, 1},
+			{0, 0, 1},
+			{1, 1, 1},
+			{0, 0, 1},
+			{1, 1, 1},
+		},
+
+		// 4
+		{
+			{1, 0, 1},
+			{1, 0, 1},
+			{1, 1, 1},
+			{0, 0, 1},
+			{0, 0, 1},
+		},
+
+		// 5
+		{
+			{1, 1, 1},
+			{1, 0, 0},
+			{1, 1, 1},
+			{0, 0, 1},
+			{1, 1, 1},
+		},
+
+		// 6
+		{
+			{1, 1, 1},
+			{1, 0, 0},
+			{1, 1, 1},
+			{1, 0, 1},
+			{1, 1, 1},
+		},
+
+		// 7
+		{
+			{1, 1, 1},
+			{0, 0, 1},
+			{0, 0, 1},
+			{0, 0, 1},
+			{0, 0, 1},
+		},
+
+		// 8
+		{
+			{1, 1, 1},
+			{1, 0, 1},
+			{1, 1, 1},
+			{1, 0, 1},
+			{1, 1, 1},
+		},
+
+		// 9
+		{
+			{1, 1, 1},
+			{1, 0, 1},
+			{1, 1, 1},
+			{0, 0, 1},
+			{1, 1, 1},
+		},
+	}
+
+	colon := placeholder{
+		{0, 0, 0},
+		{0, 1, 0},
+		{0, 0, 0},
+		{0, 1, 0},
+		{0, 0, 0},
+	}
+
+	// For Go Playground: loop 100 steps, for example.
+	for {
+		// get the current time: hour, minute, and second
+		var (
+			now            = time.Now()
+			hour, min, sec = now.Hour(), now.Minute(), now.Second()
+		)
+
+		// again, an array is used here.
+		//
+		// because, the number of placeholders in this clock
+		// is constant (which is 8 placeholders).
+		clock := [8]placeholder{
+			// separate 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],
+		}
+
+		fmt.Print(charClear)
+
+		// print the clock
+		for line := range clock[0] {
+
+			// print a line for each letter
+			for letter, v := range clock {
+				// colon blink
+				char := charDefault
+				if v == colon {
+					char = charEmpty
+					if sec%2 == 0 {
+						char = charColon
+					}
+				}
+
+				// print a line
+				for _, c := range clock[letter][line] {
+					if c == 1 {
+						fmt.Print(char)
+					} else {
+						fmt.Print(charEmpty)
+					}
+				}
+
+				fmt.Print(charSeparator)
+			}
+			fmt.Println()
+		}
+
+		// wait for 1 second
+		time.Sleep(time.Second)
+	}
+}