add: quiz and exercises to pointers

26-pointers/exercises/01-basics/solution/main.go

@@ -0,0 +1,96 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+type computer struct {
+	brand string
+}
+
+func main() {
+	// create a nil pointer with the type of pointer to a computer
+	var null *computer
+
+	// compare the pointer variable to a nil value
+	if null == nil {
+		// , and say it's nil
+		fmt.Println("null computer is nil")
+	}
+
+	// create an apple computer by putting its address to a pointer variable
+	apple := &computer{brand: "apple"}
+
+	// put the apple into a new pointer variable
+	newApple := apple
+
+	// compare the apples: if they are equal
+	if apple == newApple {
+		// say so and print their addresses
+		fmt.Printf("apples are equal          : apple: %p newApple: %p\n",
+			apple, newApple)
+	}
+
+	// create a sony computer by putting its address to a new pointer variable
+	sony := &computer{brand: "sony"}
+
+	// compare apple to sony, if they are not equal
+	if apple != sony {
+		// say so and print their addresses
+		fmt.Printf("apple and sony are inequal: apple: %p sony: %p\n",
+			apple, sony)
+	}
+
+	// put apple's value into a new ordinary variable
+	appleVal := *apple
+
+	// print apple pointer variable's address, and the address it points to
+	// and, print the new variable's addresses as well
+	fmt.Printf("apple                     : %p %p\n", &apple, apple)
+	fmt.Printf("appleVal                  : %p\n", &appleVal)
+
+	// compare the value that is pointed by the apple and the new variable
+	if *apple == appleVal {
+		// if they are equal say so
+		fmt.Println("apple and appleVal are equal")
+
+		// print the values:
+		// the value that is pointed by the apple and the new variable
+		fmt.Printf("apple                     : %+v — appleVal: %+v\n",
+			*apple, appleVal)
+	}
+
+	// change sony's brand to hp using the func
+	change(sony, "hp")
+	// print sony's brand
+	fmt.Printf("sony                      : %s\n", sony.brand)
+
+	// print the returned value
+	fmt.Printf("appleVal                  : %+v\n", valueOf(apple))
+
+	// and call the func 3 times and print the returned values' addresses
+	fmt.Printf("dell's address            : %p\n", newComputer("dell"))
+	fmt.Printf("lenovo's address          : %p\n", newComputer("lenovo"))
+	fmt.Printf("acer's address            : %p\n", newComputer("acer"))
+}
+
+// create a new function: change
+// the func can change the given computer's brand to another brand
+func change(c *computer, brand string) {
+	c.brand = brand
+}
+
+// write a func that returns the value that is pointed by the given *computer
+func valueOf(c *computer) computer {
+	return *c
+}
+
+// write a new constructor func that returns a pointer to a computer
+func newComputer(brand string) *computer {
+	return &computer{brand: brand}
+}