Add Two Numbers

1
Add Two Numbers

• In Math
• S x y
• Or
• x y S

2
Add Two Numbers In C

• Sum num1 num2
• // This is a comment
• // Semicolon Statement terminator
• // Use meaningful names
• Sum num1 num2

3
Assignment Operator

• num1 num2 Sum
• num1 num2 Sum // Wrong!
• //
  Assignment statement MUST
• // be from
  right to left
• // Not
  equal
• Sum num1 num2 // Correct!
• // Not
  equal

4
Are the two statements the same?

• Sum Num1 Num2
• Sum num1 num2
• // NO!
• // C is case sensitive!

5
Arithmetic Operators

• Addition
• Subtraction -
• Multiplication
• Division /
• What is in C?
• x y // Not good!
• What is in C?
• x y // Not good!

6
Semantics, Syntax, and Style

• x x 2
• Semantics
• Increase x by 2
• Assignment (right to left)
• Syntax
• Statement terminator
• Case sensitive
• Style
• one space before and after
• any operator

7
Precedence Rules

• From low to high
• , -
• , /
• ( )

8
Examples

• x 8 - 4 2
• // result
• x (8 - 4) 2
• // result
• y 8 / 4 2
• // result
• y 8 / (4 2)
• // result

9
More Examples

• z 8 / 4 2
• // No!
• z 8 / 4 4
• // NO!
• z 8 / 4 4
• // Result ?
• z 5 / (2 5)
• // Result 0.5 or 0?

10
Integer division vs. Float division

• In Math
• 5 is almost always the same as 5.0
• In C
• 5 is almost never the same as 5.0
• Why?
• Store value in computer as bits, bytes.
• 5 is stored as an integer
• 5.0 is stored as a float number

11
Integer Division

• 7 / 5
• Quotient 1
• Remainder 2
• 5 / 7
• Quotient 0
• Remainder 5

12
Float Division

• 7.0 / 5.0
• Quotient 1.4
• 7 / 5.0 (Same)
• 7.0 / 5 (Same)
• 5.0 / 7
• Quotient 0.714285

13
Quotient (Division) Operator

• Expression Result
• 7 / 5 1
• 14 / 5 2
• 143 / 10 14

14
Remainder (Modular) Operator

• Expression Result
• 7 5
• 14 5
• 143 10

15
Exercises

• Expression Result
• 12 20 3
• 20 12 3
• 12 / 20 3
• 20 / 12 3
• 20 / 12 3
• 20 12 3

16
Summary

• Statement Terminator
• Assignment Operator
• total total num1 // from right to
  left
• Arithmetic Operators and Precedence Rules
• -,
• /, ,
• ()
• Semantics, Syntax, and Style

17
Quiz 1 (Part II)

• Due Monday in class