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+# Lab 6 Selection Structures
+## Topic 3 Basic Program Structures
+
+## Exercise 1
+Assuming that the variable $x$ is storing $1$, determine the result of the boolean expressions below.
+```
+int x = 1;
+```
+| Boolean expressions | Result |
+| ------------------- | ------ |
+| (true) && (4 < 3) | false|
+| !(x < 0) && (x < 0) | false |
+| (x < 0) || (x > 0) | true |
+| (x != 0) || (x == 0)	 | true |
+| (x != 0) || (x == 0)	 | true |
+| (x != 0) == !(x == 0) | true |
+
+## Exercise 2
+Assuming that $x$ and $y$ are `int` type, which of the followings are legal Java expressions?
+| Expressions | legal | illegal |
+| ----------- | ----- | ------- |
+| x > y > 0	 | [] | [x] |
+| x = y || y	| [] | [x] |
+| x /= y | [x] | [x] |
+| x or y | [] | [x] |
+| x and y | [] | [x] |
+| (x != 7) || (x = 7) | [] | [x] |
+
+## Exercise 3
+What will be the value of y after the program fragment below has been executed?
+```
+int x = 4;
+int y = 4;
+switch (x + 4) {
+	case 8: y=1;
+	default: y++;
+}
+# y is 2
+```
+
+## Exercise 4
+Write a boolean expression that evaluates to true if the number x is in the range 21 to 30 inclusive, or x is negative.
+```
+(x >= 21 and x <= 30) || x < 0
+```
+
+## Exercise 5
+Rewrite the `if-else` statements below to use the `switch` statement.
+
+```java
+import java.util.Scanner;
+
+public class Ex5 {
+
+    public static void main(String[] args) {
+
+        Scanner scan = new Scanner(System.in);
+        int a;
+        int x = 0;
+
+        System.out.print("a: ");
+        a = scan.nextInt();
+
+        if (a == 1)
+            x += 3;
+        else if (a == 2)
+            x += 5;
+        else if (a == 3)
+            x += 7;
+        else
+            x += 10;
+
+        System.out.println("x = " + x);
+
+    }
+}
+```
+
+## Exercise 6
+In New York City (NYC), even numbered streets are east-bound, odd numbered streets are west-bound. Write a Java program to accept a street number from the user and print a message on screen to tell the user the direction.
+A sample execution of the program is shown below. Those in __ are user inputs.
+```
+e:\> java Ex6
+Street number? __213__
+West-bound
+```
+
+## Exercise 7
+Write a Java program to calculate the parking fee based on the vehicle type and the hours a vehicle spent in a car park. The parking fee is charged according to the table below.
+
+| Vehicle Type | Hourly Rate ($ per hour) |
+| - | - |
+| Private Car | 15 |
+| Bus | 35 |
+| Truck | 50 |
+
+Sample executions of the program are shown below. Those in __ are user inputs. All inputs (including the vehicle type) have the data type `int`.
+```
+e:\> java Ex7
+Vehicle Type [1=private, 2=bus, 3=truck]? _1_
+Number of hours? _3_
+Parking fee = 45
+```
+
+```
+e:\> java Ex7
+Vehicle Type [1=private, 2=bus, 3=truck]? _2_
+Number of hours? _2_
+Parking fee = 70
+```
+
+## Exercise 8
+Write a Java program to read an examination mark and determine the grade obtained according to the table below. Note that an examination mark may be a fractional number such as 62.5.
+
+| Mark | 0-39 | 39.1-49 | 49.1-59 | 59.1-69 | otherwise |
+| - | - | - | - | - | - |
+| Grade | F | D | C | B | A |
+
+Sample executions of the program are shown below. Those in __ are user inputs.
+
+```
+e:\> java Ex8
+Exam mark? _72.5_
+Grade = A
+```
+
+```
+e:\> java Ex8
+Exam mark? _43.5_
+Grade = D
+```