Todo

1
To-do

• Review Quiz 5 Project 5 questions
• More exercises
• Diagram memory usage of arrays
• Arrays of primitive-type variables
• Arrays of objects
• Programming exercises on arrays

2
Array variables

• Array variables are references
• double a -1.0, 4.5, 0.5
• char b A, a, B, D
• char c b //copy reference b to c

-1.0
A
a0
a
b
4.5
a
a1
0.5
B
a2
c
D
3
Diagram the memory usage of the following.

• int a0 -2, 3, 4
• int a1 new int6
• Array.Copy(a0, a1, 3)
• int a2 a1
• int a3

4
Arrays of objects

• If variable a refers to an array of objects, then
  each element in a is also a reference.
• Create an array of objects
• //First new operator allocate memory for the
  array of references Point pts new Point2
• //Following new operator allocate memory for the
  objects referred // to by the array
• pts0 new Point(1.0, 2.0)
• pts1 new Point(3.0, 4.0)

null
pts0
pts
null
pts1
x 1.0 y 2.0
pts0
pts
pts1
x 3.0 y 4.0
5
Diagram the final memory usage of the following.

• BankAccount account new BankAccount3
• account1 new BankAccount(25.0)

6
Exercise rolling a dice

• Simulate the rolling of one dice. Output the
  occurrence of each outcome for 100 tosses.
• Use a Random object to create random numbers 1
  through 6.
• Random r new Random()
• int outcome r.Next(1, 7)
• Use an array to store the occurrence times of
  each outcome
• int result new int7 //Only the last 6 are
  used
• //result1 occurrence of 1
• //result2 occurrence of 2
• //
• //result6 occurrence of 6

7
Exercie Fibonacci series

• Fibonacci series starts with 0 and 1, each new
  number in the series is simply the sum of the two
  preceeding it.
• 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, . .
  .
• Using arrays, compute the first 50 Fibonacci
  numbers, then out them.

8
Exercise class LineSegment

• Instance variable an array of two Point objects
• Point points new Point2
• // Use the class Point in example 12
• One constructor with 2 arguments to initialize
  points
• One method returning the length of the segment
• One method returning the mid-point of the segment
• ToString method returning a string representing
  the segment