fa directory created

fa/code/src/apps/ch.2.5/box_example/main.go

@@ -0,0 +1,73 @@
+package main
+
+import "fmt"
+
+const (
+	WHITE = iota
+	BLACK
+	BLUE
+	RED
+	YELLOW
+)
+
+type Color byte
+
+type Box struct {
+	width, height, depth float64
+	color                Color
+}
+
+type BoxList []Box //a slice of boxes
+
+func (b Box) Volume() float64 {
+	return b.width * b.height * b.depth
+}
+
+func (b *Box) SetColor(c Color) {
+	b.color = c
+}
+
+func (bl BoxList) BiggestsColor() Color {
+	v := 0.00
+	k := Color(WHITE)
+	for _, b := range bl {
+		if b.Volume() > v {
+			v = b.Volume()
+			k = b.color
+		}
+	}
+	return k
+}
+
+func (bl BoxList) PaintItBlack() {
+	for i, _ := range bl {
+		bl[i].SetColor(BLACK)
+	}
+}
+
+func (c Color) String() string {
+	strings := []string{"WHITE", "BLACK", "BLUE", "RED", "YELLOW"}
+	return strings[c]
+}
+
+func main() {
+	boxes := BoxList{
+		Box{4, 4, 4, RED},
+		Box{10, 10, 1, YELLOW},
+		Box{1, 1, 20, BLACK},
+		Box{10, 10, 1, BLUE},
+		Box{10, 30, 1, WHITE},
+		Box{20, 20, 20, YELLOW},
+	}
+
+	fmt.Printf("We have %d boxes in our set\n", len(boxes))
+	fmt.Println("The volume of the first one is", boxes[0].Volume(), "cm³")
+	fmt.Println("The color of the last one is", boxes[len(boxes)-1].color.String())
+	fmt.Println("The biggest one is", boxes.BiggestsColor().String())
+
+	fmt.Println("Let's paint them all black")
+	boxes.PaintItBlack()
+	fmt.Println("The color of the second one is", boxes[1].color.String())
+
+	fmt.Println("Obviously, now, the biggest one is", boxes.BiggestsColor().String())
+}