2. Introduction to Computer and Programing Thanachat Thanomkulabut

3. Outline 2  Introduction to computer  Programming Languages  C# Language Overview

4. Definition of Computer 3  Devices for performing computations at high speeds with great accuracy  A machine that can be programmed to manipulate symbols.  A machine that can quickly store and retrieve large amounts of data.  Physical components are known as “Hardware” Introduction to computer

5. Computer Categories 4 Desktop Computer Laptop, Notebook, Netbook PDA – Personal Digital Assistant Personal Computer High Computation Power Supercomputer and Mainframe Introduction to computer

6. Computer Systems  Hardware  Actual physical machines (equipment) that make up the computer 5  Software  Programs written for a specific application are often called softwares Introduction to computer

7. Computer Components CPU (Central Processing Unit)Primary storage (memory) Secondary storage (disks, tapes, etc.)Input devices (mouse, keyboard, etc.) Output devices (screen, printer, etc.) 6 Introduction to computer

8. Hardware - Process INPUT Processing Primary storage OUTPUT command Information result Secondary storage Introduction to computer

9. Computer Storage RAMROM 8 Introduction to computer Primary Storage Secondary Storage Read Only Non - Volatile Can Read/Write Volatile Much Faster More expensive Slower Less expensive Computer Storage

10. Data Representation 9  Data in computer is represented in “ bit ”  bit = binary digit 0 or 1  Byte = 8 bits  1 byte can represent many kinds of data 1 byte = 01100001 the above 1 byte represents character “a” or 97 the meaning of 1 byte depends on the program 1 Kbyte = 2 10 = 1024 bytes 1 Mbyte = 2 20 = 1,048,576 bytes 1 Gbyte = 2 30 = 1,073,741,824 bytes 1 Tbyte = 2 40 = 1,099,511,627,776 bytes Introduction to computer

11. ASCII Table 10

12. Outline 11  Introduction to computer  Programming Languages  C# Language Overview

13. Programming Languages 12  Program  A set of instructions for a computer to follow, written in specific programming language  Types of programming language  High-Level Language  Assembly Language  Machine Language Programming Languages

14. High-level VS Assembly VS Machine Language 13  High-level Language  Nearly like human word SUM := A * 2 + ALPHA/3;  Assembly Language  Some key words are understandable MULL3A, #2, R ADDL3R6, R7, SUM  Machine Language  Only “ 0 ” and “ 1 ” 00011000011 00011001111 10011000111 Computer itself understands only Machine language

15. Language translator 14 Hello World! _ High-level language static void Main( ) { Console.WriteLine("Hello World!"); } Interpreter / Compiler Assembly language pushl %ebp movl %esp, %ebp subl $8, %esp andl $-16, %esp Machine language 00011000110001110 00110001110101111 00011000110001110 Assembler Machine Programming Languages

16. High-Level Languages  Procedural Language  Fortran  Cobol  Basic  C  Pascal  Object-Oriented Language  C++  Java  C#  Functional Language  Lisp  Logic Language  Prolog 15 Programming Languages

17. Outline 16  Introduction to computer  Programming Languages  C# Language Overview

18. A simple C# Program 17 Grouping using { } C# Language Overview

19. A simple C# Program 18 A statement must be ended with semicolon “;” C# Language Overview

20. A simple C# Program 19 C# syntax is case-sensitive namespaceNAMEspace Main()main() C# Language Overview

21. A simple C# Program 20 White space means nothing static void Main(string[] args) { Console.WriteLine("Hello World!"); } static void Main(string[] args){ Console.WriteLine("Hello World!");} C# Language Overview

22. A simple C# Program 21 Anything between /* */ or after // is considered a comment Comments will not be translated C# Language Overview

23. Program Structure  The starting point of the program is:  This is known as the method Main  A method is put inside a class  A class may be put inside a namespace static void Main () {... starting point... } static void Main () {... starting point... } 22 C# Language Overview

24. Program Structure  In C#  A program can contain several namespaces  A namespace can contain several classes  A class can contain several methods  In other words  Think of a namespace as a container of classes  Think of a class as a container of methods method1 method2 namespace Class Class 23 C# Language Overview

25. Program Structure  For this 204111 course  Program with only one class and at most one namespace  For now until sometime before midterm  Program with one method (i.e., Main) namespace HelloW { class HelloWClass { static void Main () { System.Console.WriteLine("Hello World!"); System.Console.ReadLine(); } namespace HelloW { class HelloWClass { static void Main () { System.Console.WriteLine("Hello World!"); System.Console.ReadLine(); } 24 C# Language Overview

26. Naming  C# allows user to give a name to something.  A user-defined name can be any word with some rules.  Remember!!! C# is a case-sensitive language. * Case Sensitive Example KU ≠ kU ≠ku KU ≠ kU ≠ ku C# Language Overview 25

27. Naming Rules  Letters, digits and underscores(_)  First character must be a letter or _  Up to 63 characters long  Must not be a reserved word C# Language Overview 26 Example nameName _data 9point class class_Aclass_"A" point9

28. 27 Identifier examples  Valid examples  score, count, total  score1, count99, total09  score_1, count_99, total_99  myStudentId  my_student_id  Invalid examples  point&score  total-number  9points

29. 28 using System; namespace Sample1 { class Program { static void Main(string[] args) { const double payrate = 120.50; int hrs; double wages; Console.Write ("Please enter working hours : "); hrs = int.Parse(Console.ReadLine()); if (hrs > 40 ) wages = (hrs * payrate) + ((hrs-40)* payrate*2); else wages = hrs * payrate; Console.WriteLine("Employee works " + hrs + " must earn "+wages); } fDeclaration Part : This part is used to declare constant and variable. fProgram body: This part is used to put statements for execution.

30. 29 C# Program: class declaration  Class name  Member declarations  Data member  Method (or functions)  In the beginning of the class, we usually use only one method: Main --- which is where our program starts. class MainClass { public static void Main(string[] args) { const double pi = 3.1416; int radius; double area; radius = int.Parse(Console.ReadLine()); area = pi*radius*radius; Console.WriteLine(area); }

31. 30 Notes for Identifiers  Identifiers are case-sensitive  mystudentId  Mystudentid  MYSTUDENTID

32. C# Reserved Words C# Language Overview 31

33. More Resources  How Bits and Bytes Work (http://www.howstuffworks.com/bytes.htm)http://www.howstuffworks.com/bytes.htm  Byte (http://en.wikipedia.org/wiki/Byte)http://en.wikipedia.org/wiki/Byte  Computer hardware (http://en.wikipedia.org/wiki/Computer_hardware)http://en.wikipedia.org/wiki/Computer_hardware  Software (http://en.wikipedia.org/wiki/Software)http://en.wikipedia.org/wiki/Software  Programming language (http://en.wikipedia.org/wiki/Programming_language)http://en.wikipedia.org/wiki/Programming_language  List of programming languages (http://en.wikipedia.org/wiki/List_of_programming_la nguages)http://en.wikipedia.org/wiki/List_of_programming_la nguages 32

34. Any question?