update book code

eBook/examples/chapter_7/array_sum.go

@@ -1,16 +1,17 @@
-package main
-import "fmt"
-
-func main() {
-    array := [3]float64{7.0, 8.5, 9.1}
-    x := Sum(&array) // Note the explicit address-of operator
-    // to pass a pointer to the array
-    fmt.Printf("The sum of the array is: %f", x)
-}
-
-func Sum(a *[3]float64) (sum float64) {
-    for _, v := range a { // derefencing *a to get back to the array is not necessary!
-        sum += v
-    }
-    return
-}
+package main
+
+import "fmt"
+
+func main() {
+	array := [3]float64{7.0, 8.5, 9.1}
+	x := Sum(&array) // Note the explicit address-of operator to pass a pointer to the array
+	fmt.Printf("The sum of the array is: %f", x)
+}
+
+func Sum(a *[3]float64) (sum float64) {
+	for _, v := range a {   // can also with dereferencing *a to get back to the array
+		sum += v
+	}
+	return
+}
+// Output: The sum of the array is: 24.600000