Lesson 3 continued

1
Lesson 3 continued

• Math and Incrementing

2
Evaluate me

• How do you think we do this?
• x 15 6 / 3

3
Order Of Operations

• Level of Precedence Operator Associativity
• Highest ()
• unary - right to left
• / left to right
• Lowest - left to right
• Just remember your Aunt Sally

4
Try Me!

• (56)/(9-7)
• 18 / 5 4 3
• 1 3 5 - 2

5
Answer

• (56)/(9-7) -gt 11/2 -gt 5

6
Answer

• 18 / 5 4 3 -gt 3 4 3 -gt 12 3 -gt 0

7
Answer

• 1 3 5 - 2 -gt 1 3 - 2 -gt 4 - 2 -gt 2

8
Lab 3.1 Easter

• Divide y by 19 and call the remainder a. Ignore
  the quotient.
• int a y 19

9
Easter Try Me

• Divide b 8 by 25 and get a quotient f. Ignore
  the remainder.

10
Easter Is this right?

• Divide b 8 by 25 and get a quotient f. Ignore
  the remainder.
• Is this answer right or wrong?
• int f b 8 / 25

11
Easter Correct Answer

• Divide b 8 by 25 and get a quotient f. Ignore
  the remainder.
• int f (b 8) / 25

12
Incrementing and Decrementing

• You will soon see that it is very common to have
  to add amount to a number and save the new value.
• int x 5x x 8 //Add 8 to x and save it
  in x

13
A Shortcut

• Instead of
• x x 8
• Use can do this
• x 8

14
Others Assignment Shortcuts

• You can also do
• -, , /,
• Example
• int x 100
• x - 10
• //after this, x will have the //value 90

15
Adding or Subtracting 1

• Incrementing or Decrementing by 1 is very common,
  so we have an even better short cut
• Instead of
• x x 1
• Or even
• x 1
• You can
• x
• Or
• x
• There is also a --
• Example x--

16
Be Careful

• x means add after everything else on this line
• x means add before everything else on this line

17
Be Careful

• int a1, b
• b a
• After execution of the above code
• a 2 and b 2
• int a1, b
• b a
•  After execution of the above code
• a 2 and b 1
•