match: pointers code to videos

26-pointers/02-pointers-basic-examples/main.go

@@ -16,44 +16,45 @@ func main() {
 		P       *int
 	)
 
-	if P == nil {
-		fmt.Printf("P is nil and its address is %p\n", P)
-	}
-
 	counter = 100 // counter is an int variable
 	P = &counter  // P is a pointer int variable
 	V = *P        // V is a int variable (a copy of counter)
 
-	if P == &counter {
-		fmt.Printf("P's address is equal to counter: %p == %p\n", P, &counter)
+	if P == nil {
+		fmt.Printf("P is nil and its address is %p\n", P)
 	}
 
-	fmt.Printf("counter : %-16d address: %-16p\n", counter, &counter)
-	fmt.Printf("P       : %-16p address: %-16p *P: %-16d\n", P, &P, *P)
-	fmt.Printf("V       : %-16d address: %-16p\n", V, &V)
+	if P == &counter {
+		fmt.Printf("P is equal to counter's address: %p == %p\n", 
+			P, &counter)
+	}
 
-	fmt.Println("\n••••• CHANGE: counter")
+	fmt.Printf("counter: %-13d addr: %-13p\n", counter, &counter)
+	fmt.Printf("P      : %-13p addr: %-13p *P: %-13d\n", P, &P, *P)
+	fmt.Printf("V      : %-13d addr: %-13p\n", V, &V)
+
+	fmt.Println("\n••••• change counter")
 	counter = 10 // V doesn't change because it's a copy
-	fmt.Printf("counter : %-16d address: %-16p\n", counter, &counter)
-	fmt.Printf("V       : %-16d address: %-16p\n", V, &V)
+	fmt.Printf("counter: %-13d addr: %-13p\n", counter, &counter)
+	fmt.Printf("V      : %-13d addr: %-13p\n", V, &V)
 
-	fmt.Println("\n••••• CHANGE IN: passVal")
+	fmt.Println("\n••••• change counter in passVal()")
 	counter = passVal(counter)
-	fmt.Printf("counter : %-16d address: %-16p\n", counter, &counter)
+	fmt.Printf("counter: %-13d addr: %-13p\n", counter, &counter)
 
-	fmt.Println("\n••••• CHANGE IN: passPtrVal")
+	fmt.Println("\n••••• change counter in passPtrVal()")
 	passPtrVal(&counter) // same as passPtrVal(&counter) (no need to return)
 	passPtrVal(&counter) // same as passPtrVal(&counter) (no need to return)
-	fmt.Printf("counter : %-16d address: %-16p\n", counter, &counter)
+	fmt.Printf("counter: %-13d addr: %-13p\n", counter, &counter)
 }
 
 // *pn is a int pointer variable (copy of P)
 func passPtrVal(pn *int) {
-	fmt.Printf("pn      : %-16p address: %-16p *pn: %d\n", pn, &pn, *pn)
+	fmt.Printf("pn     : %-13p addr: %-13p *pn: %d\n", pn, &pn, *pn)
 
 	// pointers can breach function isolation borders
 	*pn++ // counter changes because `pn` points to `counter` — (*pn)++
-	fmt.Printf("pn      : %-16p address: %-16p *pn: %d\n", pn, &pn, *pn)
+	fmt.Printf("pn     : %-13p addr: %-13p *pn: %d\n", pn, &pn, *pn)
 
 	// setting it to nil doesn't effect the caller (the main function)
 	pn = nil
@@ -62,6 +63,6 @@ func passPtrVal(pn *int) {
 // n is a int variable (copy of counter)
 func passVal(n int) int {
 	n = 50 // counter doesn't change because `n` is a copy
-	fmt.Printf("n       : %-16d address: %-16p\n", n, &n)
+	fmt.Printf("n      : %-13d addr: %-13p\n", n, &n)
 	return n
 }

26-pointers/03-pointers-composites/main.go

@@ -26,7 +26,7 @@ func main() {
 	structs()
 }
 
-// -----------------------------------------------------------------------------
+// ••••••••••••••••••••••••••••••••••••••••••••••••••
 
 type house struct {
 	name  string
@@ -43,7 +43,11 @@ func structs() {
 
 	addRoomPtr(&myHouse)
 	fmt.Printf("structs()     : %p %+v\n", &myHouse, myHouse)
+}
 
+func addRoomPtr(h *house) {
+	h.rooms++ // same: (*h).rooms++
+	fmt.Printf("addRoomPtr()  : %p %+v\n", h, h)
 	fmt.Printf("&myHouse.name : %p\n", &myHouse.name)
 	fmt.Printf("&myHouse.rooms: %p\n", &myHouse.rooms)
 }
@@ -53,19 +57,11 @@ func addRoom(h house) {
 	fmt.Printf("addRoom()     : %p %+v\n", &h, h)
 }
 
-func addRoomPtr(h *house) {
-	// (*h).rooms++
-	h.rooms++
-	fmt.Printf("addRoomPtr()  : %p %+v\n", h, h)
-}
-
-// -----------------------------------------------------------------------------
+// ••••••••••••••••••••••••••••••••••••••••••••••••••
 
 func maps() {
 	confused := map[string]int{"one": 2, "two": 1}
-
 	fix(confused)
-
 	fmt.Println(confused)
 
 	// &confused["one"]
@@ -77,7 +73,7 @@ func fix(m map[string]int) {
 	m["three"] = 3
 }
 
-// -----------------------------------------------------------------------------
+// ••••••••••••••••••••••••••••••••••••••••••••••••••
 
 func slices() {
 	dirs := []string{"up", "down", "left", "right"}
@@ -89,29 +85,30 @@ func slices() {
 	fmt.Printf("slices list   : %p %q\n", &dirs, dirs)
 }
 
-func up(list []string) {
-	for i := range list {
-		list[i] = strings.ToUpper(list[i])
-		fmt.Printf("up.list[%d]    : %p\n", i, &list[i])
-	}
-	// *list = append(*list, "HEISEN BUG")
-	list = append(list, "HEISEN BUG")
-
-	fmt.Printf("up list       : %p %q\n", &list, list)
-}
-
 func upPtr(list *[]string) {
 	lv := *list
 
 	for i := range lv {
 		lv[i] = strings.ToUpper(lv[i])
 	}
+
 	*list = append(*list, "HEISEN BUG")
 
 	fmt.Printf("upPtr list    : %p %q\n", list, list)
 }
 
-// -----------------------------------------------------------------------------
+func up(list []string) {
+	for i := range list {
+		list[i] = strings.ToUpper(list[i])
+		fmt.Printf("up.list[%d]    : %p\n", i, &list[i])
+	}
+
+	list = append(list, "HEISEN BUG")
+
+	fmt.Printf("up list       : %p %q\n", &list, list)
+}
+
+// ••••••••••••••••••••••••••••••••••••••••••••••••••
 
 func arrays() {
 	nums := [...]int{1, 2, 3}
@@ -126,7 +123,6 @@ func arrays() {
 
 func incr(nums [3]int) {
 	fmt.Printf("incr nums     : %p\n", &nums)
-
 	for i := range nums {
 		nums[i]++
 		fmt.Printf("incr.nums[%d]  : %p\n", i, &nums[i])
@@ -134,8 +130,8 @@ func incr(nums [3]int) {
 }
 
 func incrByPtr(nums *[3]int) {
+	fmt.Printf("incrByPtr nums: %p\n", &nums)
 	for i := range nums {
-		nums[i]++
-		// (*nums)[i]++
+		nums[i]++ // same: (*nums)[i]++
 	}
 }