fix: coding style and file format for all example.

eBook/examples/chapter_11/interfaces.go

@@ -1,30 +1,31 @@
-package main
-
-import "fmt"
-
-type Shaper interface {
-	Area() float32
-	// Perimeter() float32
-}
-
-type Square struct {
-	side float32
-}
-
-func (sq *Square) Area() float32 {
-	return sq.side * sq.side
-}
-
-func main() {
-	sq1 := new(Square)
-	sq1.side = 5
-
-	// var areaIntf Shaper
-	// areaIntf = sq1
-	// shorter, without separate declaration:
-	// areaIntf := Shaper(sq1) 
-	// or even:
-	areaIntf := sq1
-	fmt.Printf("The square has area: %f\n", areaIntf.Area())
-}
-// The square has area: 25.000000
+package main
+
+import "fmt"
+
+type Shaper interface {
+	Area() float32
+	// Perimeter() float32
+}
+
+type Square struct {
+	side float32
+}
+
+func (sq *Square) Area() float32 {
+	return sq.side * sq.side
+}
+
+func main() {
+	sq1 := new(Square)
+	sq1.side = 5
+
+	// var areaIntf Shaper
+	// areaIntf = sq1
+	// shorter, without separate declaration:
+	// areaIntf := Shaper(sq1)
+	// or even:
+	areaIntf := sq1
+	fmt.Printf("The square has area: %f\n", areaIntf.Area())
+}
+
+// The square has area: 25.000000