fix: coding style and file format for all example.

eBook/examples/chapter_4/pointer.go

@@ -1,12 +1,12 @@
-package main
-
-import "fmt"
-
-func main() {
-	var i1 = 5
-	fmt.Printf("An integer: %d, its location in memory: %p\n", i1, &i1)
-
-	var intP *int
-	intP = &i1
-	fmt.Printf("The value at memory location %p is %d\n", intP, *intP) 
-}
+package main
+
+import "fmt"
+
+func main() {
+	var i1 = 5
+	fmt.Printf("An integer: %d, its location in memory: %p\n", i1, &i1)
+
+	var intP *int
+	intP = &i1
+	fmt.Printf("The value at memory location %p is %d\n", intP, *intP)
+}