Csc153 chapter 01
- 1. Microsoft Visual C# 2010 Fourth Edition Chapter 1 A First Program Using C#
- 2. Objectives • Learn about programming • Learn about procedural and object-oriented programming • Learn about the features of object-oriented programming languages • Learn about the C# programming language • Write a C# program that produces output • Learn how to select identifiers to use within your programs Microsoft Visual C# 2010, Fourth Edition 2
- 3. Objectives (cont'd.) • Improve programs by adding comments and using the System namespace • Write and compile a C# program using the command prompt and using Visual Studio Microsoft Visual C# 2010, Fourth Edition 3
- 4. Programming • Computer program – Set of instructions that tells a computer what to do – Also called software • Software comes in two broad categories – System software – Application software • Machine language – Expressed as a series of 1s and 0s • 1s represent switches that are on, and 0s represent switches that are off Microsoft Visual C# 2010, Fourth Edition 4
- 5. Programming (cont'd.) • High-level programming languages – Use reasonable terms such as “read,” “write,” or “add” • Instead of the sequence of on/off switches that perform these tasks – Allows you to assign reasonable names to areas of computer memory – Has its own syntax (rules of the language) • Compiler – Translates high-level language statements into machine code Microsoft Visual C# 2010, Fourth Edition 5
- 6. Programming (cont'd.) • Programming logic – Involves executing the various statements and procedures in the correct order • To produce the desired results • Debugging – Process of removing all syntax and logical errors from the program Microsoft Visual C# 2010, Fourth Edition 6
- 7. Procedural and Object-Oriented Programming • Procedural program – Create and name computer memory locations that can hold values (variables) – Write a series of steps or operations to manipulate those values • Identifier – A one-word name used to reference a variable • Procedures or methods – Logical units that group individual operations used in a computer program – Called or invoked by other procedures or methods Microsoft Visual C# 2010, Fourth Edition 7
- 8. Procedural and Object-Oriented Programming (cont'd.) • Object-oriented programming – An extension of procedural programming • Objects – Similar to concrete objects in the real world – Contain their own variables and methods – Attributes of an object represent its characteristics – State of an object is the collective value of all its attributes at any point in time – Behaviors of an object are the things it “does” Microsoft Visual C# 2010, Fourth Edition 8
- 9. Procedural and Object-Oriented Programming (cont'd.) • Originally used for two types of applications – Computer simulations – Graphical user interfaces (GUIs) Microsoft Visual C# 2010, Fourth Edition
- 10. Features of Object-Oriented Programming Languages • Classes – A category of objects or a type of object – Describes the attributes and methods of every object that is an instance, or example, of that class • Objects – An instance of a class • Encapsulation – Technique of packaging an object’s attributes and methods into a cohesive unit; undivided entity – Using a black box Microsoft Visual C# 2010, Fourth Edition 10
- 11. Features of Object-Oriented Programming Languages (cont'd.) • Interface – Interaction between a method and an object • Inheritance – Provides the ability to extend a class to create a more specific class • Polymorphism – Describes the ability to create methods that act appropriately depending on the context Microsoft Visual C# 2010, Fourth Edition 11
- 12. The C# Programming Language • Developed as an object-oriented and component- oriented language • Part of Microsoft Visual Studio 2010 • Allows every piece of data to be treated as an object and to consistently employ the principles of object-oriented programming • Contains a GUI interface that makes it similar to Visual Basic Microsoft Visual C# 2010, Fourth Edition 12
- 13. The C# Programming Language (cont'd.) • Modeled after the C++ programming language – However, eliminates some of the most difficult features to understand in C++ • Very similar to Java – In C#, simple data types are objects Microsoft Visual C# 2010, Fourth Edition 13
- 14. Writing a C# Program that Produces Output class literal string argument namespace method Microsoft Visual C# 2010, Fourth Edition 14
- 15. Writing a C# Program that Produces Output (cont'd.) • Namespace – Provides a way to group similar classes • C# method parts – Method header • Includes the method name and information about what will pass into and be returned from a method – Method body • Contained within a pair of curly braces and includes all the instructions executed by the method Microsoft Visual C# 2010, Fourth Edition 15
- 16. Writing a C# Program that Produces Output (cont'd.) • Whitespace – Any combination of spaces, tabs, and carriage returns (blank lines) – Organizes your code and makes it easier to read • Access modifier – Defines the circumstances under which the method can be accessed • Keywords – Predefined and reserved identifiers that have special meaning to the compiler Microsoft Visual C# 2010, Fourth Edition 16
- 17. Writing a C# Program that Produces Output (cont'd.) • The name of the method is Main() – Every application must have a Main() method – Classes with a Main() method are called application classes; others are non-application classes • The method returns nothing as indicated by the keyword void Microsoft Visual C# 2010, Fourth Edition
- 18. Selecting Identifiers • Requirements – Must begin with an underscore, at sign (@), or letter • Letters include foreign-alphabet letters – Can contain only letters, digits, underscores, and the at sign • Not special characters such as #, $, or & – Cannot be a C# reserved keyword Microsoft Visual C# 2010, Fourth Edition 18
- 19. Microsoft Visual C# 2010, Fourth Edition 19
- 20. Selecting Identifiers (cont'd.) Microsoft Visual C# 2010, Fourth Edition 20
- 21. Selecting Identifiers (cont'd.) Microsoft Visual C# 2010, Fourth Edition 21
- 22. Selecting Identifiers (cont'd.) Microsoft Visual C# 2010, Fourth Edition 22
- 23. Improving Programs by Adding Program Comments • Program comments – Nonexecuting statements that document a program • Comment out – Turn a statement into a comment • Types of comments in C# – Line comments – Block comments – XML-documentation format comments Microsoft Visual C# 2010, Fourth Edition 23
- 24. Adding Program Comments (cont'd.) Microsoft Visual C# 2010, Fourth Edition 24
- 25. Using the System Namespace Microsoft Visual C# 2010, Fourth Edition 25
- 26. Using the System Namespace (cont'd.) Microsoft Visual C# 2010, Fourth Edition 26
- 27. Writing and Compiling a C# Program • Steps for viewing a program output – Compile source code into intermediate language (IL) – C# just in time (JIT) compiler translates the intermediate code into executable statements • You can use either of two ways to compile – The command line – The Integrated Development Environment (IDE) Microsoft Visual C# 2010, Fourth Edition 27
- 28. Compiling Code from the Command Prompt • What to do if you receive an operating system error message – Command csc • Stands for “C Sharp compiler” Microsoft Visual C# 2010, Fourth Edition 28
- 29. Compiling Code from the Command Prompt (cont'd.) • What to do if you receive a programming language error message – Program error messages start with the program name – Followed by the line number and position within the line of the error Microsoft Visual C# 2010, Fourth Edition
- 30. Compiling Code from within the Visual Studio IDE • Advantages of using the Visual Studio IDE – Some of the code you need is already created for you – The code is displayed in color – You can double-click an error message and the cursor will move to the line of code that contains the error – Other debugging tools are available Microsoft Visual C# 2010, Fourth Edition 30
- 31. Compiling Code from within the Visual Studio IDE (cont'd.) Microsoft Visual C# 2010, Fourth Edition 31
- 32. You Do It • Enter your first C# program into a text editor so you can execute it • Use any text editor to write the following code and save it as Hello.cs Microsoft Visual C# 2010, Fourth Edition 32
- 33. Compiling and Executing a Program from the Command Line • Type the command that compiles your program: csc Hello.cs Microsoft Visual C# 2010, Fourth Edition 33
- 34. Compiling and Executing a Program from the Command Line (cont'd.) • Execute the program Hello.exe Microsoft Visual C# 2010, Fourth Edition 34
- 35. Compiling and Executing a Program Using the Visual Studio IDE • Steps – Create a new project (console application) – Enter the project name – Write your program using the editor – To compile the program, click Build on the menu bar, and then click Build Solution • As an alternative, you can press F6 – Click Debug on the menu bar and then click Start Without Debugging Microsoft Visual C# 2010, Fourth Edition 35
- 36. Compiling and Executing a Program Using the Visual Studio IDE (cont'd.) Microsoft Visual C# 2010, Fourth Edition 36
- 37. Compiling and Executing a Program Using the Visual Studio IDE (cont'd.) Microsoft Visual C# 2010, Fourth Edition 37
- 38. Compiling and Executing a Program Using the Visual Studio IDE (cont'd.) Microsoft Visual C# 2010, Fourth Edition 38
- 39. Deciding Which Method to Use • Advantage of using the command line – Saves disk space • Advantages of using the Visual Studio IDE – Automatic sentence completion – Words are displayed using different colors based on their category – Code automatically generated by the IDE is very helpful when writing a GUI Microsoft Visual C# 2010, Fourth Edition 39
- 40. Adding Comments to a Program • Line comment example // Filename Hello.cs // Written by <your name> // Written on <today’s date> • Block comment example /* This program demonstrates the use of the WriteLine() method to print the message Hello, world! */ Microsoft Visual C# 2010, Fourth Edition 40
- 41. Summary • A computer program is a set of instructions that tell a computer what to do • Understand differences between procedural programming and object-oriented programming • Objects are instances of classes and are made up of attributes and methods • The C# programming language is an object- oriented and component-oriented language • System.Console.WriteLine() method – Produces a line of console output Microsoft Visual C# 2010, Fourth Edition 41
- 42. Summary (cont'd.) • You can define a C# class or variable by using any name or identifier • Comments are nonexecuting statements that you add to document a program – Or to disable statements when you test a program • Use namespaces to improve programs • To create a C# program, you can use the Microsoft Visual Studio environment Microsoft Visual C# 2010, Fourth Edition 42