feat: update go smaples with our class discussion

Author: 1995parham

08-arrays-and-slices/main.go

@@ -19,25 +19,34 @@ func main() {
 	fmt.Printf("s2: %v\n", s2)
 	fmt.Printf("s1 after \"s2[0] = 10\": %v\n", s1)
 
+	// append a new element into our newly created slice.
+	s2 = append(s2, 120)
+	fmt.Printf("s2: %v\n", s2)
+	fmt.Printf("s1 after \"append(s2, 120)\": %v\n", s1)
+
+	// create another slice from middle of s1
+	s3 := s1[2:4]
+	fmt.Printf("s3: %v, cap(s3): %d, len(s3): %d\n", s3, cap(s3), len(s3))
+
 	a1 := [3]int{1, 2, 3}
 
-	s3 := a1[1:3]
-	s3[0] = 20
+	s4 := a1[1:3]
+	s4[0] = 20
 
-	fmt.Printf("s3: %v\n", s3)
+	fmt.Printf("s4: %v\n", s4)
 	fmt.Printf("a1 after \"s3[0] = 20\": %v\n", a1)
 
-	s4 := s3
+	s5 := s4
 
 	// compile error: slice can only be compared to nil
-	// fmt.Printf("s4 ? s3: %v\n", s4 == s3)
-	fmt.Printf("s4: %v\n", s4)
+	// fmt.Printf("s5 ? s4: %v\n", s5 == s4)
+	fmt.Printf("s5: %v\n", s5)
 
 	// panic: runtime error: index out of range [3] with length 2
-	// fmt.Printf("invalid access to slice \"s4[3]\": %d", s4[3])
+	// fmt.Printf("invalid access to slice \"s5[3]\": %d", s5[3])
 
 	// compile error: invalid array index 3 (out of bounds for 3-element array)
 	// fmt.Printf("invalid access to array \"a1[3]\": %d", a1[3])
 
-	fmt.Printf("s4[1:]: %v\n", s4[1:])
+	fmt.Printf("s5[1:]: %v\n", s5[1:])
 }

09-map/main.go

@@ -45,4 +45,12 @@ func main() {
 	if ok {
 		fmt.Printf("opinions[%s] = %v\n", "Hesam", opinion)
 	}
+
+	delete(opinions, "Parham")
+	delete(opinions, "Parham")
+
+	_, ok = opinions["Parham"]
+	if !ok {
+		fmt.Printf("opinions[%s] does not exist\n", "Parham")
+	}
 }

10-structs/main.go

@@ -6,6 +6,9 @@ type Student struct {
 	Name   string
 	Family string
 	age    int
+
+	// uncomment the following line to remove the comparablity.
+	// justForFun []int
 }
 
 // New is a popular pattern to create types
@@ -37,6 +40,11 @@ func main() {
 		age:    27,
 	}
 
+	newS := s
+	if newS == s {
+		fmt.Println("we can compare student structs")
+	}
+
 	fmt.Println(s)
 
 	s.nothing()