1. 1 nd Semester 2007 1 Module6 Review Thanawin Rakthanmanon Email: fengtwr@ku.ac.th Create by: Aphirak Jansang Computer Engineering Department Kasetsart University, Bangkok THAILAND

2. 1 nd Semester 2007 2 Sentinel Loops: example static void Main() { int N, SUM; int N, SUM; SUM = 0; SUM = 0; N = 0; N = 0; while (N != -1) { while (N != -1) { SUM = SUM+N; SUM = SUM+N; Console.Write( ” Enter number or -1 to quit”); Console.Write( ” Enter number or -1 to quit”); N = int.Parse(Console.ReadLine()); N = int.Parse(Console.ReadLine()); } Console.WriteLine(“The sum is {0}.”, SUM); Console.WriteLine(“The sum is {0}.”, SUM);} Console.Write( ” Enter number or -1 to quit”); N = int.Parse(Console.ReadLine()); Question 1 st Time (redundant part)

3. 1 nd Semester 2007 3 Problem – Triangle shape static void Main() { int N=0, M=0; for ( ; ; ) { for ( ; ; ) { Console.Write(”*”); } Console.WriteLine(); } *** *** M = 3 M > 0 M-- QUIZ static void Main() { int N=0, M=0; for ( ; ; ) { for ( N=0 ; N<M ; N++ ) { Console.Write(”*”); } Console.WriteLine(); } *** ** * M = 3 M > 0 M-- N = 3 N >= MN >= MN >= MN >= M N--

4. 1 nd Semester 2007 4 Introduction to Computer & Programming  What is RAM and ROM ?  What is main memory & secondary memory ?  What is high-level language ?  Which type of language C# is, machine, assembly, high-level ?  1000110 2 = ?

5. 1 nd Semester 2007 5 Program Structure namespace method1 method2 Class Class namespace HelloW { class HelloWClass { static void Main () { System.Console.WriteLine(“Hello"); } namespace HelloW { class HelloWClass { static void Main () { System.Console.WriteLine(“Hello"); } method3 method1 method2 Class namespace :::: Program structure in this semester

6. 1 nd Semester 2007 6 Naming Rules (for Identifier)  Letters(a-z, A-Z), digits(0-9) and underscores(_)  First character  letter or _  Up to 63 characters long  Must not be a reserved word * Case Sensitive Example KU66 ≠ kU66 ≠ku66 KU66 ≠ kU66 ≠ ku66

7. 1 nd Semester 2007 7 C# Reserved Words

8. 1 nd Semester 2007 8 Variable Declaration  Syntax: ;  Example:  We can also assign its initial value. Example: int radius; double area; int a,b,c; bool isokay; int k = 200; bool done = false; Variable must be declared before used

9. 1 nd Semester 2007 9 Variable & Data Types TypeSizeDescriptionRange bool1 byteStore truth valuetrue / false char1 byteStore one charactercharacter code 0 – 255 byte1 byteStore positive integer0 – 255 short2 byteStore integer-32,768 -- 32,767 int4 byteStore integer-2.1 x 10 9 -- 2.1 x 10 9 long8 byteStore integer-9.2 x 10 18 -- 9.2 x 10 18 double16 byteStore real number± 5.0x10 -324 -- ± 1.7x10 308 stringN/AStore sequence of characters N/A Variable must be declared before used

10. 1 nd Semester 2007 10 Boolean expression Operators  Comparison = Equal = != Not equal != < Less < > Greater > <= Less than or equal to <= >= Greater than or equal to >=  Boolean && And && || Or || ! Not !

11. 1 nd Semester 2007 11 Arithmetic expression  Operators + - * / % (remainder after division) 11 % 2  1 //true if Y is even (Y%2 == 0) //true if Y is even //true if Y is even (Y%2 != 1) //true if Y is even   Example (x > 12) && (x < 20)   will be true if x is between 12 and 20 If x is 10, the above is false If x is 15, the above is true

12. 1 nd Semester 2007 12 The Math Class  The Math class inside the System namespace provides a large collection of math methods and constants  Some examples: Method/ Constant Value returnedExample CallResult PI Value of  Math.PI3.1415927 Max(x,y) Larger of the twoMath.Max(1,2)2 Abs(x) Absolute value of x Math.Abs(-1.3)1.3 Sqrt(x) Square-root of x Math.Sqrt(4.0)2.0 Round(x) Nearest integer to x Math.Round(0.8)1 Pow(x,y) xyxy Math.Pow(3,2)9.0 Log(x) Natural log of x Math.Log(10)2.302585 Ceiling(x) Smallest integer greater than or equal to x Math.Ceiling(4.1)5 Cos(x) Cosine of x radiansMath.Cos(Math.PI)

13. 1 nd Semester 2007 13 Incrementing Operators  Operators ++ and -- can be used to increment and decrement a variable's value by 1, respectively  Example: Stateme nt Description x++ Add 1 to the variable x x-- Subtract 1 to the variable x int n = 0; n++; // is equivalent to n = n+1, or n += 1 n++; // n is now 2 n--; // n is now 1 int n = 0; n++; // is equivalent to n = n+1, or n += 1 n++; // n is now 2 n--; // n is now 1

14. 1 nd Semester 2007 14 Modify-And-Assign Operations  Arithmetic operators can be combined with "=" to produce a modify-and-assign operation  Ex. StatementDescription var += expression Increment var by the value of expression var -= expression Decrement var by the value of expression var *= expression Multiply var by the value of expression, then store the result in var var /= expression Divide var by the value of expression, then store the result in var sum += x; // is equivalent to sum = sum + x prod *= 2.5; // is equivalent to prod = prod * 2.5 y -= 3+a; // is equivalent to y = y – (3+a)

15. 1 nd Semester 2007 15 Statements  A statement is a unit of command to instruct your program  A method consists of one or more statements class Hello { static void Main () { System.Console.WriteLine("Hello World!"); System.Console.ReadLine(); } class Hello { static void Main () { System.Console.WriteLine("Hello World!"); System.Console.ReadLine(); } Statement#1 Statement#2

16. 1 nd Semester 2007 16 Statement Types  Assignment Statement  Input Statement  Output Statement

17. 1 nd Semester 2007 17 Assignment Statement  Assigning value to variable  Syntax: = ; = ; int Width,High; Width=10;High=5; int Width = 10; int High = 5;

18. 1 nd Semester 2007 18 Input Statement  Console.ReadLine()  Return string Use to get the input from user  Convert string to other data type int.Parse() Convert string to integer double.Parse() Convert string to double Example string st; st = System.Console.ReadLine();

19. 1 nd Semester 2007 19 Example: Input Statement Ex1: string myname; myname = System.Console.ReadLine(); Ex2: int Width,High; string temp1; temp1 = System.Console.ReadLine(); Width = int.Parse(temp1); temp1 = System.Console.ReadLine(); High = int.Parse(temp1);

20. 1 nd Semester 2007 20 Output Statements  Use the method Write or WriteLine in the Console class (which is in System namespace)  Basic usage:  Advanced usage:  Even more advanced usage: Console.WriteLine(”Size {0}x{1}”, width, height); double salary=12000; Console.WriteLine("My salary is {0:f2}.", salary); Console.WriteLine("Hello");Console.WriteLine(area);

21. 1 nd Semester 2007 21 Control Structure  if/else  switch  While / do while  for  nested if  nested loop

22. 1 nd Semester 2007 22 if statement ”condition”true  Execute the specific statement when the ”condition” becomes true  Syntax: if (condition) statement; //true statement; //true if (condition) { statement1; //true statement1; //true statement2; //true statement2; //true}

23. 1 nd Semester 2007 23 if…else… statement conditiontrue statement1  If condition is true  execute statement1 conditionfalse statement2  If condition is false  execute statement2  Syntax: if (condition) statement1; //true statement1; //trueelse statement2; //false if (condition) statement1; //true statement1; //true else { statement2; //false statement2; //false statement3; //false }

24. 1 nd Semester 2007 24 Nested if statement int N; N = int.Parse(Console.ReadLine()); if (N >= 0) { if (N==0) if (N==0) Console.WriteLine(“N is zero number”); Console.WriteLine(“N is zero number”); else else Console.WriteLine(“N is positive number”); Console.WriteLine(“N is positive number”);}else Console.WriteLine(“N is negative number”); Console.WriteLine(“N is negative number”); if#1 if#2

25. 1 nd Semester 2007 25 Nested if statement int N; N = int.Parse(Console.ReadLine()); if (N >= 0) { if (N==0) if (N==0) Console.WriteLine(“N is zero number”); Console.WriteLine(“N is zero number”); else else Console.WriteLine(“N is positive number”); Console.WriteLine(“N is positive number”);}else Console.WriteLine(“N is negative number”); Console.WriteLine(“N is negative number”); if#1 if#2 QUIZ How to write this program without nested if ?

26. 1 nd Semester 2007 26 Nested if statement int N; N = int.Parse(Console.ReadLine()); #1if (N >= 0) #2{ #3 if (N==0) #4 Console.WriteLine(“N is zero number”); #5 else #6 Console.WriteLine(“N is positive number”); #7} #8 else #9 Console.WriteLine(“N is negative number”); if#1 if#2 Answer if ((N>=0) && (N==0)) // or (N==0) Console.WriteLine(“N is zero number”); Console.WriteLine(“N is zero number”); if ((N>=0) && !(N==0)) // or (N>0) Console.WriteLine(“N is positive number”); Console.WriteLine(“N is positive number”); if (N < 0) Console.WriteLine(“N is negative number”); Console.WriteLine(“N is negative number”);

27. 1 nd Semester 2007 27 Switch-case example char op; Console.Write("Select + - / * :"); op=char.Parse(Console.ReadLine()); switch (op) { case '+': Console.Write("{0}+{1}={2}", x,y,x+y); break; case '-': Console.Write("{0}-{1}={2}", x,y,x-y); break; : default: Console.Write("Try again"); break; } must be int, char, string must be int, char, string int day_num; day_num= int.Parse(Console.ReadLine()); switch( day_num ) { case 1: Console.Write ("Sunday"); break; case 2: console.Write("Monday"); break; : default : Console.Write(“Try again"); break; } <expression> int version char version

28. 1 nd Semester 2007 28 Switch-case example (continue) string op; Console.Write("Select + - / * :"); op=Console.ReadLine(); switch (op) { case “+”: Console.Write("{0}+{1}={2}", x,y,x+y); break; case “-”: Console.Write("{0}-{1}={2}", x,y,x-y); break; : default: Console.Write("Try again"); break; } must be int, char, string must be int, char, string string version <expression>

29. 1 nd Semester 2007 29 Flowchart Symbols Overview  Graphical representation Terminator Process Input/output Condition Connector Flow line

30. 1 nd Semester 2007 30 Flowchart of if statement statement1 if (condition) statement2; //true statement2; //true else { statement3; //false statement3; //false} statement4; true false CONDITION START statement1 statement2 statement3 statement4

31. 1 nd Semester 2007 31 Flowchart of Switch-case statement1 label int day_num; day_num= int.Parse(Console.ReadLine()); switch( day_num ) { case 1: Console.Write ("Sunday"); break; case 2: console.Write("Monday"); break; : default : Console.Write(“Try again"); break; } (day_num) label=1 label=2 default statement2 statement n (day_num=3) label=3 statement3 :::: (day_num=2) (day_num=1)

32. 1 nd Semester 2007 32 While statement while (condition) statement; statement; while (condition) { statement-1; statement-1; statement-2; statement-2;... statement-N; statement-N;} For Multiple Statements For Single Statement

33. 1 nd Semester 2007 33 How this partial code works? static void Main() { int N, SUM; int N, SUM; SUM = 0; SUM = 0; N = 0; N = 0; while (N >= 0) { while (N >= 0) { Console.Write(”Please input N: ”); Console.Write(”Please input N: ”); N = int.Parse(Console.ReadLine()); N = int.Parse(Console.ReadLine()); if (N>=0) if (N>=0) SUM = SUM+N; SUM = SUM+N; } Console.WriteLine(“SUM = {0}”, SUM); Console.WriteLine(“SUM = {0}”, SUM);} How to exit this loop?

34. 1 nd Semester 2007 34 How this partial code works? static void Main() { int N, J; int N, J; J = int.Parse(Console.ReadLine()); J = int.Parse(Console.ReadLine()); N = 1; N = 1; while ( ) { while ( ) { if ( ) if ( ) Console.WriteLine(”{0}”, N); Console.WriteLine(”{0}”, N); }} N <= J N++; How to display odd number between 1 – J on screen? N%2==0 2 4 6 8... QUIZ Display only even number between 1 to J

35. 1 nd Semester 2007 35 do…while statement do { statement; statement; } while (condition); do{ statement-1; statement-1; statement-2; statement-2;. statement-N; statement-N; } while (condition); For Multiple Statements For Single Statement

36. 1 nd Semester 2007 36 Sentinel Loops: do…while static void Main() { int N, SUM; int N, SUM; SUM = 0; SUM = 0; N = 0; N = 0; do do { Console.Write( ” Enter number or -1 to quit”); Console.Write( ” Enter number or -1 to quit”); N = int.Parse(Console.ReadLine()); N = int.Parse(Console.ReadLine()); if (N!= -1) if (N!= -1) SUM = SUM+N; SUM = SUM+N; } while (N != -1); } while (N != -1); Console.WriteLine( ” The sum is {0}.”, SUM); Console.WriteLine( ” The sum is {0}.”, SUM);} How to rewrite with while loop?

37. 1 nd Semester 2007 37 While / Do While WHILE (pre-checking) DO WHILE (post-checking)

38. 1 nd Semester 2007 38 For statement for ( [initializers]; [expression]; [iterators] ) statement; statement; For Multiple Statements For Single Statement for ( [initializers]; [expression]; [iterators] ) { statement-1; statement-1; statement-2; statement-2;.. statement-N; statement-N;}

39. 1 nd Semester 2007 39 For statement for ( [initializers]; [expression]; [iterators] ) statement; statement;STARTSTARTENDEND expressionexpression true false StatementStatement iteratorsiterators initializersinitializers

40. 1 nd Semester 2007 40 Display 10 to 100 on screen static void Main() { int i; int i; for ( ; ; ) { for ( ; ; ) { Console.WriteLine(“{0}”, i); Console.WriteLine(“{0}”, i); }} static void Main() { int i; int i; i = 10; i = 10; while (i <= 100) { while (i <= 100) { Console.WriteLine(“{0}”, i); Console.WriteLine(“{0}”, i); i++; i++; }} while version for version i=10 ; i<=100 ; i++ QUIZ

41. 1 nd Semester 2007 41 More Variations  Display 0,2,4,...,20  Display 1,3,5,...,19  Display 15,12,9,...,0 for (i = 1; i <= 19; i += 2) Console.WriteLine(i); for (i = 1; i <= 19; i += 2) Console.WriteLine(i); for (i = 15; i >= 0; i -= 3) Console.WriteLine(i); for (i = 15; i >= 0; i -= 3) Console.WriteLine(i); for (i = 0; i <= 20; i += 2) Console.WriteLine(i); for (i = 0; i <= 20; i += 2) Console.WriteLine(i); Try !