.Net Framework 2 fundamentals
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.Net Framework 2 fundamentals

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.Net Framework 2 fundamentals

.Net Framework 2 fundamentals

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.Net Framework 2 fundamentals .Net Framework 2 fundamentals Presentation Transcript

  • Chapter -1Framework Fundamentals
    HarshanaWeerasinghe
    http://www.harshana.info
    http://Blog.harshana.info
  • Framework Fundamentals
    Create a console or Windows Forms application in Visual Studio.
    Add namespaces and references to system class libraries to a project.
    Run a project in Visual Studio, set breakpoints, step through code, and watch the values of variables.
    By Harshana Weerasinghe (http://www.harshana.info)
    2
  • Types
    Mainly 2 types in Microsoft .Net
    Value Type
    Reference Type
    By Harshana Weerasinghe (http://www.harshana.info)
    3
  • Value Types
    Value types are variables that contain their data directly instead of containing a reference to the data stored elsewhere in memory. Instances of value types are stored in an area of memory called the stack, where the runtime can create, read, update, and remove them quickly with minimal overhead.
    By Harshana Weerasinghe (http://www.harshana.info)
    4
  • Built-in Value Types
    By Harshana Weerasinghe (http://www.harshana.info)
    5
  • Other Value Types
    By Harshana Weerasinghe (http://www.harshana.info)
    6
  • Declare Value Types
    <type> <VariableName> [= <Default Value>];
    boolbolTestVariable= false;
    Nullable<bool>b= null;
    Or
    bool? b = null;
    By Harshana Weerasinghe (http://www.harshana.info)
    7
  • Create User-Defined Types
    structCycle
    {
    // Private fields
    int_val, _min, _max;
    // Constructor
    public Cycle(intmin, intmax)
    {
    _val = min;
    _min = min;
    _max = max;
    }
    public intValue
    {
    get { return _val; }
    set
    {
    if (value > _max)
    _val = _min;
    else
    {
    if (value < _min)
    _val = _max;
    else
    _val = value;
    }
    }
    }
    public override string ToString()
    {
    return Value.ToString();
    }
    public intToInteger()
    {
    return Value;
    }
    }
    By Harshana Weerasinghe (http://www.harshana.info)
    8
  • Using Operators (new in .NET 2.0)*
    public static Cycle operator +(Cycle arg1, int arg2)
    {
    arg1.Value += arg2;
    return arg1;
    }
    public static Cycle operator -(Cycle arg1,intarg2)
    {
    arg1.Value -= arg2;
    return arg1;
    }
    By Harshana Weerasinghe (http://www.harshana.info)
    9
  • Use User-Defined Types
    Cycle degrees =new Cycle(0, 359);
    Cycle quarters= new Cycle(1, 4);
    for (int i = 0; i <= 8; i++)
    {
    degrees += 90; quarters += 1;
    Console.WriteLine("degrees = {0}, quarters = {1}", degrees, quarters);
    }
    By Harshana Weerasinghe (http://www.harshana.info)
    10
  • Enumerations
    enumTitles : int{ Mr, Ms, Mrs, Dr };
    Titles t = Titles.Dr;
    Console.WriteLine("{0}.", t);// Displays "Dr."
    By Harshana Weerasinghe (http://www.harshana.info)
    11
  • Reference Types
    Reference types store the address of their data, also known as a pointer, on the stack. The actual data that address refers to is stored in an area of memory called the heap. The runtime manages the memory used by the heap through a process called garbagecollection. Garbage collection recovers memory periodically as needed by disposing of items that are no longer referenced.
    By Harshana Weerasinghe (http://www.harshana.info)
    12
  • Built-in Reference Types
    By Harshana Weerasinghe (http://www.harshana.info)
    13
  • Strings and String Builders
    string s="this is some text to search";
    s = s.Replace("search", "replace");
    Console.WriteLine(s);
    string s;
    s = "wombat"; // "wombat“
    s += " kangaroo";// "wombat kangaroo“
    s += " wallaby"; // "wombat kangaroo wallaby“
    s += " koala";// "wombat kangaroo wallaby koala”
    Console.WriteLine(s);
    By Harshana Weerasinghe (http://www.harshana.info)
    14
  • String Builder
    using System.Text;
    StringBuildersb =new StringBuilder(30);
    sb.Append("wombat");// Build string.
    sb.Append(" kangaroo");
    sb.Append(" wallaby");
    sb.Append(" koala");
    string s = sb.ToString(); // Copy result to string.
    Console.WriteLine(s);
    By Harshana Weerasinghe (http://www.harshana.info)
    15
  • Create and Sort Arrays
    // Declare and initialize an array.
    int[] ar = { 3, 1, 2 };
    // Call a shared/static array method.
    Array.Sort(ar);
    // Display the result.
    Console.WriteLine("{0}, {1}, {2}", ar[0], ar[1], ar[2]);
    By Harshana Weerasinghe (http://www.harshana.info)
    16
  • Streams
    Streams are another very common type because they are the means for reading from and writing to the disk and communicating across the network. The System.IO.Streamtype is the base type for all task-specific stream types.
    By Harshana Weerasinghe (http://www.harshana.info)
    17
  • Streams Cont…
    using System.IO;
    // Create and write to a text file
    StreamWritersw =new StreamWriter("text.txt");
    sw.WriteLine("Hello, World!");
    sw.Close();
    // Read and display a text file
    StreamReadersr =new StreamReader("text.txt");
    Console.WriteLine(sr.ReadToEnd());
    sr.Close();
    By Harshana Weerasinghe (http://www.harshana.info)
    18
  • Throw and Catch Exceptions
    StreamReadersr = new StreamReader("text.txt");
    try
    {
    Console.WriteLine(sr.ReadToEnd());
    }
    catch (Exception ex)
    {
    // If there are any problems reading the file, display an error message
    Console.WriteLine("Error reading file: " + ex.Message);
    }
    finally
    {
    // Close the StreamReader, whether or not an exception occurred
    sr.Close();
    }
    By Harshana Weerasinghe (http://www.harshana.info)
    19
  • Constructing Classes
    public class Cycle
    {
    // Private fields
    int_val, _min, _max;
    // Constructor
    public Cycle(intmin,intmax)
    {
    _val = min;
    _min = min;
    _max = max;
    }
    //Property
    public intValue
    {
    get { return _val; }
    set { _val = value; }
    }
    //Method
    public string MyValue()
    {
    return _val.ToString();
    }
    }
    By Harshana Weerasinghe (http://www.harshana.info)
    20
  • Inheritance – Animal Class
    class Animal
    {
    string m_Name;
    intm_Age;
    public Animal(string _Name)
    {
    this.Name = _Name;
    }
    public string Name
    {
    get { return m_Name; }
    set { m_Name = value; }
    }
    public intAge
    {
    get { return m_Age; }
    set { m_Age = value; }
    }
    public string Speak()
    {
    return "Hello Animal";
    }
    }
    By Harshana Weerasinghe (http://www.harshana.info)
    21
  • Cat n Dog Classes
    class Cat : Animal
    {
    double m_Weight;
    public double Weight
    {
    get { return m_Weight; }
    set { m_Weight = value; }
    }
    public string Speak()
    {
    return "Meaw, Meaw";
    }
    }
    class Dog : Animal
    {
    //Default Ctor
    public Dog()
    {
    }
    //Other Ctor
    public Dog(string _Name,int_Age)
    : base(_Name)//Call Base Class Ctor
    {
    this.Age = _Age;
    }
    public string Speak()
    {
    if (this.Age >3)
    return " Grr.. Grr..";
    else
    return " Buhh.. Buhh..";
    }
    }
    By Harshana Weerasinghe (http://www.harshana.info)
    22
  • Interfaces
    Interfaces, also known as contracts, define a common set of members that all classes that implement the interface must provide. For example, the IComparable interface defines the CompareTo method, which enables two instances of a class to be compared for equality. All classes that implement the IComparable interface, whether custom-created or built in the .NET Framework, can be compared for equality.
    By Harshana Weerasinghe (http://www.harshana.info)
    23
  • By Harshana Weerasinghe (http://www.harshana.info)
    24
  • Sample
    interface IMessage
    {
    // Send the message. Returns True is success, False otherwise.
    boolSend();
    // The message to send.
    string Message { get; set; }
    // The Address to send to.
    string Address { get; set; }
    }
    class EmailMessage : IMessage
    {
    public boolSend()
    {
    throw new Exception("The method or operation is not implemented.");
    }
    public string Message
    {
    get
    {
    throw new Exception("The method or operation is not implemented.");
    }
    set
    {
    throw new Exception("The method or operation is not implemented.");
    }
    }
    public string Address
    {
    get
    {
    throw new Exception("The method or operation is not implemented.");
    }
    set
    {
    throw new Exception("The method or operation is not implemented.");
    }
    }
    }
    By Harshana Weerasinghe (http://www.harshana.info)
    25
  • Commonly used interfaces
    By Harshana Weerasinghe (http://www.harshana.info)
    26
  • Partial Classes - new in .NET 2.0
    Partial classes allow you to split a class definition across multiple source files. The benefit of this approach is that it hides details of the class definition so that derived classes can focus on more significant portions.
    By Harshana Weerasinghe (http://www.harshana.info)
    27
  • Generics
    Generics are part of the .NET Framework's type system that allows you to define a type while leaving some details unspecified. Instead of specifying the types of parameters or member classes, you can allow code that uses your type to specify it. This allows consumer code to tailor your type to its own specific needs.
    By Harshana Weerasinghe (http://www.harshana.info)
    28
  • Generics Cont..
    class Obj
    {
    public Object t;
    public Object u;
    public Obj(Object _t,Object _u)
    {
    t = _t;
    u = _u;
    }
    }
    class Gen<T, U>
    {
    public T t;
    public U u;
    public Gen(T _t, U _u)
    {
    t = _t;
    u = _u;
    }
    }
    By Harshana Weerasinghe (http://www.harshana.info)
    29
  • Generics Cont..
    // Add two strings using the Obj class
    Objoa =new Obj("Hello, ", "World!");
    Console.WriteLine((string)oa.t + (string)oa.u);
    // Add two strings using the Gen class
    Gen<string, string>ga = new Gen<string, string>("Hello, ", "World!");
    Console.WriteLine(ga.t + ga.u);
    // Add a double and an int using the Obj class
    Objob =new Obj(10.125, 2005);
    Console.WriteLine((double)ob.t + (int)ob.u);
    // Add a double and an int using the Gen class
    Gen<double,int> gb = new Gen<double, int>(10.125, 2005);
    Console.WriteLine(gb.t + gb.u);
    By Harshana Weerasinghe (http://www.harshana.info)
    30
  • Generics Cont..
    // Add a double and an int using the Gen class
    Gen<double, int> gc = new Gen<double,int>(10.125, 2005);
    Console.WriteLine(gc.t + gc.u);
    // Add a double and an int using the Obj class
    Objoc =new Obj(10.125, 2005);
    Console.WriteLine((int)oc.t + (int)oc.u);
    last line contains an error— the oc.tvalue is cast to an Int instead of to a double. Unfortunately, the compiler won't catch the mistake. Instead, a run-time exception is thrown when the runtime attempts to cast a double to an Int value.
    By Harshana Weerasinghe (http://www.harshana.info)
    31
  • Events
    By Harshana Weerasinghe (http://www.harshana.info)
    32