Sams Teach Yourself C# in 24 Hours

By James Foxall and Wendy Haro-Chun

• Table of Contents
  • Copyright
  • About the Authors
  • Acknowledgments
  • Tell Us What You Think!
  • Introduction
  • Audience and Organization
  • Conventions Used in This Book
  • Onward and Upward!
  • Part I. The Visual Studio Environment
  • Hour 1. A C# Programming Tour
  • Hour 2. Navigating C#
  • Hour 3. Understanding Objects and Collections
    • Understanding Objects
    • Understanding Properties
    • Understanding Methods
    • Building an Object Example Project
    • Understanding Collections
    • Using the Object Browser
    • Summary
    • Q&A
    • Workshop
  • Hour 4. Understanding Events
  • Part II. Building a User Interface
  • Hour 5. Building FormsPart I
  • Hour 6. Building FormsPart II
  • Hour 7. Working with the Traditional Controls
  • Hour 8. Advanced Controls
  • Hour 9. Adding Menus and Toolbars to Forms
  • Hour 10. Drawing and Printing
  • Part III. Making Things HappenProgramming!
  • Hour 11. Creating and Calling Methods
  • Hour 12. Using Constants, Data Types, Variables, and Arrays
  • Hour 13. Performing Arithmetic, String Manipulation, and Date/Time Adjustments
  • Hour 14. Making Decisions in C# Code
  • Hour 15. Looping for Efficiency
  • Hour 16. Debugging Your Code
  • Hour 17. Designing Objects Using Classes
  • Hour 18. Interacting with Users
  • Part IV. Working with Data
  • Hour 19. Performing File Operations
  • Hour 20. Controlling Other Applications Using Automation
  • Hour 21. Working with a Database
  • Part V. Deploying Solutions and Beyond
  • Hour 22. Deploying a Solution
  • Hour 23. Introduction to Web Development
  • Hour 24. The 10,000-Foot View
  • Appendix A. Answers to Quizzes/Exercises

Understanding Methods

In addition to properties, most objects have methods. Methods are actions the object can perform, in contrast to attributes that describe the object. To understand this distinction, think about the Pet object example. A Dog object has a certain set of actions that it can perform. These actions, called methods in C#, include barking and tail wagging. Figure 3.6 illustrates the Dog object and its methods.

Figure 3.6 Invoking a method causes the object to perform an action.

Triggering Methods

Think of methods as functions—which is exactly what they are. When you invoke a method, code is executed. You can pass data to the method, and methods may return values. However, a method is neither required to accept parameters (data passed by the calling code) nor required to return a value; many methods simply perform an action in code. Invoking (triggering) a method is similar to referencing the value of a property; you first reference the object's name, then a "dot," then the method name, followed by a set of parentheses, which can optionally contain any parameters that must be passed to the method.

{ObjectName}.{Method}();

For example, to make the hypothetical Dog object Bruno bark using C# code, you would use this line of code:

Bruno.Bark();

Invoking methods is simple; the real skill lies in knowing what methods an object supports and when to use a particular method.

Understanding Method Dynamism

Properties and methods go hand in hand, and at times a particular method may become unavailable because of one or more property values. For example, if you were to set the NumberofLegs on the Dog object Bruno equal to zero, the Walk and Fetch methods would obviously be inapplicable. If you were to set the NumberofLegs property back to four, you could then trigger the Walk or Fetch methods again. In C#, a method or property won't physically become unavailable—you can still call it, but doing so might cause an exception (error) or the call may be ignored.

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