1. On September 18, 1998, the International Corporation for Assigned Names and Numbers (ICANN) was started, an organization that controls the naming of websites.
2. For each of the following sequences of symbols, describe which can be valid Java identifiers and which cannot be; if you believe they cannot be, briefly explain why (e.g., "is a reserved word" or "does not start with a letter"):
3. The following formula enables us to compute the area a of a right triangle with sides x and y:
1
a = - xy
2
Assuming that x and y are already placed in the corresponding variables of type double, write a
Java code statement for assigning the corresponding value to the variable a of type double. Explain,
step-by-step, which arithmetic operations will be performed first, which next, etc., and
trace the computations on the above example.
Describe two different ways to avoid getting 0 as the result of evaluating 1/2.
Explain what happens if you simply write xy in
your Java code.
4-5. To register a website for several years, you need to pay a per-year registration fee. For simplicity, let us take $35 as this fee. Write the main method which asks the user for the URL of the website, asks for how many years we want to register this website, and prints a memo describing the price. For example, if we want to register CS website for 3 years, your program should print the following message:
From: ICANN To register your website, you need to pay $35 X 3 = $105.Declare 35 as an integer constant, so that it will be easy to change if needed.
Reminder: to read from the keyboard, you can define the reader as follows:
Scanner reader = new Scanner(System.in);the header of the main method is:
public static void main(String[] args){
6. Suppose that would like to add 2 to the number of years. If the number of years is stored in the integer variable years, which of the two lines of code leads to a correct increase: