Class 8    M 2/6    Comp 110


Program 4 questions
Branches


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Quick Review
Branches
   Simple
   Chained
   Nested
Compound condition

Examples: 

Simple branch
   if( x > 5 ) System.out.println("A");

Chained - one branch after another.
   if( x > 5 ) SOP("A");
   if( x < 10 ) SOP("B");

or

   if( x > 5 ) SOP("A");
   else SOP("C");
   if( x < 10 ) SOP("B");

Nested - one branch inside another
   if( x > 5 ) {
      if( x > 10 ) SOP("A");
      else SOP("B");
   }

Compound condition - more than one question asked
  if( x > 10 && x < 5) SOP("A");
  else SOP("B");



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In-class exercise. Answers to 1 and 2 included.

1) What is displayed if x is
a) 4  b) 5  c) 6  d) 9  e) 10  f) 11

   i) if( x > 5 ) SOP("A");
      else if( x < 10 ) SOP ("B");
           else SOP("C");

  ii) if( x > 5 ) {
         SOP("A");
         if( x < 10 ) SOP("B");
         } 
      else SOP("C");



Answer: i) a)B  b)B c)A  d)A  e)A  f)A
ii) a)C  b)C  c)A B (on 2 lines)  d) A B (on 2 lines)
e)A  f)A


2) Write a fragment of code that will test whether an
integer variable, score contains a valid test score.
Valid test scores are in the range 0 to 100.
Print valid or invalid. The code segments starts with

Scanner keyboard = new Scanner(System.in);
int x = keyboard.nextInt();


Write 3 separate versions of this code:

a) Use nested if statements
b) Use chained if statements
c) Use a single if statement with a compound condition

Answer
a) if( x >= 0 )
      if( x <= 100 ) SOP("valid");
      else SOP("invalid");
   else SOP("invalid");

b) if( x < 0 ) SOP("invalid");
   if( x > 100 ) SOP("invalid");
   else SOP("valid");

   String result = "valid";
   if( x < 0 ) result = "invalid";
   if( x > 100 ) result = "invalid";
   SOP( result );

c) if( x >= 0 && x <= 100 ) SOP("valid");
   else SOP("invalid");



3) What is the output from the following 

i) 
int x = 5;
if( x >= 5 ) SOP("A");
SOP("B");

ii)
int x = 5;
if( x >= 5 ) SOP("A");
else SOP("B");


4) 3) You are writing a program that asks the user to give a
yes-or-no response. It will accept either "y" or "yes" as an
affirmative response.

Assume the program reads the
user's response into a String variable called response.

String response = keyboard.nextLine();

Why doesn't the following work?

if( response.equals("yes" || "y") ) SOP("true");

if( response.equals("yes")  || 
    response.equals("y") )



5)  What is the value of each of the following boolean expressions if
x=5  y=10  and z=15?

a) ( x < 5 && y > x )
b) ( x < 5 || y > x)
c) ( x > 3 || y < 10 && z == 15 )
d) ( ! (x > 3) && x != z || x + y == z)


6) The service charge for cashing a check depends on the amount of the
check. If check amount , $10, charge $1. If check amount is greater
than $10 but less than $100, charge 10% of the amount. If amount is
greater than $100 but less than $1000, charge $5 + 5% of amount.
If amount > $1000, charge $40 + 1% of amount.

Given  int amount = keyboard.nextInt();
Write if statements to print out the amount of the charge.

Also, do you notice anything incomplete about this problem?