1. C# and the .NET Framework
More Control Structures and Types

2. Conditional Operators

3. Evaluating an example of a conditional AND expression

4. Evaluating an example of a conditional OR expression

5. Evaluating a logical complement expression

6. Evaluating a conditional AND expression

7. Evaluating a condition OR expression

8. relational < > <= >= equality == != conditional AND &&
Highest
NOT! !
multiplicative * / %
additive
relational < > <= >=
equality == !=
conditional AND &&
conditional OR ||
assignment = += -= *= /= %=
Lowest
Operator precedence*

9. If-else statement to choose between two alternatives
if (score >= 60 && score < 80)
Console.WriteLine
("Score " + score + " receives a C");
else
("Score " + score + " receives a B or an A");
If-else statement to choose between two alternatives

10. Nested if-else statement to choose among three alternatives
if (score >= 60 && score < 80)
Console.WriteLine("Score " + score + " receives a C");
else if (score >=80 && score < 90)
Console.WriteLine("Score " + score + " receives a B");
else
Console.WriteLine("Score " + score + " receives an A");
Nested if-else statement to choose among three alternatives

11. if (score >= 60 && score < 80)
Console.WriteLine("Score " + score + " receives a C");
else if (score >= 80 && score < 90)
Console.WriteLine("Score " + score + " receives a B");
else if (score >= 90 && score <= 100)
Console.WriteLine("Score " + score + " receives an A");
Improved version

12. Nested if format if ( Is it the first alternative? ){
First alternative code }
else if ( Is it the second alternative? ) {
Second alternative code
...
else if ( Is it the last alternative? ) {
Last alternative code
else {
Code when none of the above alternatives is true

13. Flow chart for nested if-else statements
True
Test1?
Test1 true code
False
True
Test2?
Test2 true code
False
...
False
True
Last?
Last true code
False
Last false code
Flow chart for nested if-else statements

14. Incorrect attempt to pair an else with an if
if (score >= 60)
if (score >= 80)
Console.WriteLine("You got a B or an A");
else
Console.WriteLine("You got a D or an F"); // Wrong pairing
// else does not pair with first if
Incorrect attempt to pair an else with an if

15. Corrected pairing of else and if
if (score >= 60)
if (score >= 80)
Console.WriteLine("You got a B or an A");
else
Console.WriteLine("You got a C"); // Correct pairing
// Pair else with nearest if
Corrected pairing of else and if

16. rewritten as an if-else with nested if
if (score >= 60) {
if (score >= 80)
Console.WriteLine("You got a B or an A"); }
else
// Paired to first 'if'
Console.WriteLine("You got a D or an F");
rewritten as an if-else with nested if

17. switch format switch (test_expression) { case expression1: statement1;
break;
case expression2:
statement2;
.....
default:
default_statement; }

18. An example of a switch statement
switch(mark) {
case 0:
case 1:
case 2:
case 3:
case 4: System.out.println("F");
break;
case 5: System.out.println("D");
case 6:
case 7: System.out.println("C");
case 8: System.out.println("B");
case 9:
case10: System.out.println("A");
default:System.out.println("Incorrect score"); }
An example of a switch statement

19. for (initialize; test; update) for_statement int sum = 0;
for (int i = 1; i <= 4; i++)
sum += i;
A for statement pattern and example for the sum

20. Trace of execution of the for loop
initialize
i = 1
test
1 <= 4 is true
execute body
sum += 1
(result: sum = = 1)
update
i++
(result: i = 2)
2 <= 4 is true
sum += 2
(result: sum = = 3)
(result: i = 3)
3 <= 4 is true
sum += 3
(result: sum = = 6)
(result: i + 4)
4 <= 4 is true
sum += 4
(result: sum = = 10)
(result: i = 5)
5 <= 4 is false
Trace of execution of the for loop

21. A for statement for the sum 1+3+5+7+9
int sum = 0;
for (int i = 1; i < 10; i += 2)
sum += i;
A for statement for the sum

22. A for statement for the sum 4+3+2+1
int sum = 0;
for (int i = 4; i >= l; i--)
sum += i;
A for statement for the sum

23. Declaring an index variable before the for loop
int i; // declare loop index
int sum = 0;
for (i = 4; i >= 1; i--) // initialize loop index
sum += i;
...
i += 17; // use variable i
Declaring an index variable before the for loop

24. Syntax for the do statement
while (condition) ;
Syntax for the do statement

25. Pseudocode for example 4.5 enhancement
Compute balance as in Example 4.5
Ask the user -- Repeat or Quit?
} while (User chooses to repeat);
Pseudocode for example 4.5 enhancement

26. char type Represents characters Use single quote ‘a’, ‘B’
Internally 16 bits
ASCII table in appendix
Unicode represents thousands of characters
We use ASCII for English
\ is the escape character, gives special meaning to next character

27. Escape sequences for special characters
Meaning \n
newline, move to the start of the next line \t
tab \b
backspace \r
return, move to the start of the current line
\"
double quote
\\backlash
Escape sequences for special characters

28. Additional primitive types
long -9,223,372,036,854,775,808 to
9,223,372,036,854,775,807
long bigNumber = L;
sbyte, byte, short, ushort -- integer types, special uses
float -- decimal type, 7 place accuracy
float size = 4.56F;
uint, ulong, decimal

29. Enumerations Provides convenient names for values
enum Color {Red, Green, Blue}
Declare variables
Color c = Color.Red;
Test
if ( c == Color.Green)
// do something

30. Powers and Roots Math.Pow(2.0,3.0) returns 8.0 // 2 cubed
Math.Pow(3.0,2.0) returns 9.0 // 3 squared
Math.Sqrt(2.0) returns
Math.Sqrt(16.0) returns 4.0

31. Maximum and Minimum Math.Max(3, 4) returns 4
Math.Min(3, 4) returns 3
Math.Min(17.32, ) returns
Math.Min(-9, -11) returns -11

32. Absolute value Math.Abs(x) = x, if x >= 0 = -x, if x < 0
Math.Abs(-10) returns 10
Math.Abs(12.34) returns

33. Floor and Ceiling Math.Floor(25.194) returns 25.0
Math.Ceiling(25.194) returns
Math.Ceiling( ) returns

34. Trigonometric and Exponential
Math.Sin( Math.PI ) returns
Math.Cos(Math.PI) returns
Math.Tan(Math.PI/4) returns 1
Math.Exp(1.0) returns
Math.Exp(2.0) returns
Math.Log(Math.E) returns 1
Math.Log(10.0) returns

35. Pattern for a menu-driven application
do {
choice = IO.GetInt("Choose: \n"
+ "1. Convert from meters to yds,ft,in \n"
+ "2. Convert from yds,ft,in to meters \n"
+ "3. Quit: ");
int choice = Io.readInt("Enter your choice, 1, 2 or 3");
switch (choice) {
case 1:
MetricToEnglish();
break;
case 2:
EnglishToMetric();
case 3: Console.WriteLine("Bye, Have a nice day"); }
} while (choice != 3);
Pattern for a menu-driven application