BKIndex dotnet lecture01 session1 module1 2 3 4 5 operators constructs arrays

Chapter Objectives  Explain the need for C#  Discuss flow control of a C# program  Explain the fundamental data types in C#  Discuss the concept of Boxing and UnBoxing  Discuss Structures in C#  Discuss Enumeration types Programming in C# /  Compile and run a C# program Chapter 1/ of 39 Microsoft net  Represents a new platform for developing windows & web applications  Supports more than 20 languages  Revolutionizes facilities available for Windows programming Programming in C# / Chapter 1/ of 39 Introduction to C#  Takes full advantage of the net Platform  The most efficient compiler in the net family  A modern replacement for C++  Enhances developer productivity and increases safety, by enforcing script type checking  Allows restricted use of native pointers Programming in C# / Chapter 1/ of 39 C# Program Flow  A simple C# program: Programming in C# / Chapter 1/ of 39 C# Constructs (1)  Variables in C# are declared as follows: Programming in C# / Chapter 1/ of 39 C# Constructs (2)  If you want to use any keyword as the variable name, you have to prefix the variable name with @ Programming in C# / Chapter 1/ of 39 Default Values (1)  Variables in C# are automatically assigned a default value upon creation  Output: Programming in C# / Chapter 1/ of 39 Default Values (2)  The default values of the common data types: Programming in C# / Chapter 1/ of 39 Input / Output In C# (1)  Uses methods of the Console class in the System namespace  The most widely used methods are: Programming in C# / Chapter 1/ 10 of 39 Fundamental Types Of C# (1)  C# divides data types into two fundamental categories: - int, char and structures - classes, interfaces, arrays and strings Programming in C# / Chapter 1/ 25 of 39 Fundamental Types Of C# (2)  Holds a value in the memory  Stored in a stack  Contains the address of the object in the heap  = null means that no object has been in C# / Programming Chapter 1/ 26 of 39 referenced Value Types  Example:  Output: Programming in C# / Chapter 1/ 27 of 39 Reference Types  Example: Output: Programming in C# / Chapter 1/ 28 of 39 Value types vs Reference types Programming in C# / Chapter 1/ 29 of 39 Boxing & Unboxing [1]  Boxing is the conversion of a value type into a reference type  Unboxing is the conversion of a reference type into a value type Programming in C# / Chapter 1/ 30 of 39 Boxing & Unboxing (2) Programming in C# / Chapter 1/ 31 of 39 Data Types In C#  C# provides a Unified Type System  All data types in C#, are derived from just one class, the object class Programming in C# / Chapter 1/ 32 of 39 Static Members  Members are not associated with any particular object other than the class itself  Only one instance is possible Programming in C# / Chapter 1/ 33 of 39 Arrays  A group of values of similar data type  It belongs to the reference type and hence, are stored on the heap  The declaration of arrays in C#, follow the syntax given below: DataType[number of elements] ArrayName; Programming in C# / int[6] arr1;Chapter 1/ 34 of 39 Structures  Custom data Types  Can have methods  Can have constructors  Cannot implement inheritance Programming in C# / Chapter 1/ 35 of 39 Enumerators (1)  They are a set of named constants Programming in C# / Chapter 1/ 36 of 39 Enumerators (2)  Enumerators in C# have numbers associated with the values  By default, the first element of enum is assigned a value of and is incremented for each subsequent enum element Programming in C# / Chapter 1/ 37 of 39 Enumerators (3)  The default value can be overridden during initialization Programming in C# / Chapter 1/ 38 of 39 Compiling & Running  Step – Type your code in Notepad  Step – Save the file with a cs extension  Step – Switch to DOS prompt and type the following command: csc csc First.cs  Step - To run the C# file, Programming type the name in C# / of Chapter 1/ 39 of 39 the file (First) without the