Learn .net with c#

Role of Common Language Run-Time(CLR) in .net framework

2011-11-24T12:40:00.001-08:00

The CLR is very important part of .net framework. It is execution engine for .net framework application. It also provides important capabilities in optimizing, securing and providing many robust capabilities such as application deployment and side by side execution.

CLR provides no. of services that includes-

Code management(loading and execution)
application memory isolation
veryfication of type safety
conversion of IL to Native
Access to metadata(enhance type information)
Managing memory for managed objects
Enforcement of code access security
Exception handling, including cross-language exception
Interoperation between managed code, COM objects, and pre-existing DLL(Unmanaged code and Data)
Automation of object layout
Support for developer service(profiling, debugging and so on)

Unboxing

2011-08-16T11:23:00.000-07:00

Unboxing is an explicit conversion from the object to value type or from an interface type to a value type that implements the interface.
An unboxing operation consists of:
* Checking the object instance to make sure it is a boxed value of the given value type.
* coping the value from the instance into the value type variable.

Boxing

2011-07-05T12:22:00.000-07:00

Boxing is an implicit conversion of a value type to a reference type. Consider the following value type variable.
           int a=12;
now boxing operation on above variable,
         object o=i; //boxing
Above statement create an object, on the stack, that references a value of type int, on the heap. this value is a copy of the vaue-type value assigned to the variable a. we ca understand it by following fig.

It also possible, but never needed to perform the boxing explicitly as in the following example:
           int a=12;
           object o= (object) i;

.Net Plateform

2011-07-05T00:08:00.001-07:00

The .Net Plateform is a set of technologies. The Microsoft .Net Plateform consists of the following core technologies:

The .net framework
The .net enterprise server
Building block services
Visual studio .net

Dereference Operator(*)

2011-07-04T11:06:00.000-07:00

We know that pointer is a variable that holds memory address of another variable. We can directly access the value of a variable using a pointer pointing to address of that variable. For this we will use the indirection operator (*) also known as dereference operator(*). By placing the dereference operator before a pointer variable, we can access the variable whose address is stored in the pointer. Let us an Example:
int a=65;
int *p=&a;
Now, in our program, if we place '*' before p then we can access the variable whose address is stored in p. Since p contains address of variable a, we can access variable a by writing *p. So we can use *p in place of varible name a. For Example.
*p=2 is equivalent to a=2..
(*p)++ is equivalent to a++.
The dereference operator can be read as "value pointed by" or "value at the address". For example * p can be read as "value at the address p" or " value pointed by p".

Address Opertor(&)

2011-06-29T11:33:00.000-07:00

Address operator also known as reference operator '&'. Address operator '&' returns the address of a variable when place before it. The address that locates a variable within memory is what we call a reference to that variable. Address operator '&' can be read as "address of". For example:
&a means "address of a"
&salary means "address of salary"
int a=45;

suppose at runtime a is placed in the memmory address 1886.

b=a;
this will assign the value of a to the variable b.
c=&a;
this will assign the address of variable a to the variable c. The variable that store the reference of another variable(like c) is what we call a pointer.

Comments in C#

2011-06-23T11:14:00.000-07:00

C# supports two styles of comment:.
1. Multiline comment: Multiline comment must begin with /* and end with */. Anything between these two comment symbol is ignored by compiler.
Example:
                 /* This is a
                     multiline comment
                     example */
2. Single Line comment: A single line comment begins with // and end at the end of the line.
Example:
                //single line comment example

Data Types

2011-06-22T11:08:00.000-07:00

Variables are declared as being of particular type, and each variable is constrained to hold only values of its declared type. C# is type safe language.
Variable can hold either value types or reference types, or they can be pointers.

Pointers

2011-06-21T13:04:00.000-07:00

A pointer is a variable that holds the memory address of another variable. In c#, pointer can only be declared to hold the memory address of value types(except in the case of arrays).
Pointers are declared implicitly using the dereferencer Symbol *,
int *p;
   Some programmer place the dereferencer symbol immediately after the type name.
int* p;
   This variation appears to work just as well as the previous one. this declaration sets upa pointer "p", which will pointto the initial memory address of an integer(stored in four bytes).

MS Visual studio.net: Output

2011-06-12T05:21:00.000-07:00

Output window, located on bottom left corner of MS visual studio.net. It display the result of your project compilation. When you compile your project, all errors, warnings and compilation results will be displayed in this window.

MS Visual studio.net: Creating a Project

2011-06-12T04:24:00.000-07:00

To create a new project, open MS visual studio.net:
1. Click on File menu
2.Choose New and then choose "Project"

It will give you many options. First you must select a type from the left side of the popup. You may choose visual basic project or visual c# projects based on the language you plan to use for development. Now you can choose template from the right side. you may choose windows application, asp.net web application or any other template based on the nature of the application you want. Give the name of project and specify location where you want to save the project. Then click on "Ok".

MS Visual studio.Net:Solution Explorer

2011-06-12T03:13:00.000-07:00

Solution Explorer is usually located on "top right corner" of MS visual studio.net. All the projects included in each solution and the list of files in each project are listed in the form of tree control.
When you create a MS Visual studio project, a solution will be automatically created. To add a new file to your project, you can right click on the project name in the solution explorer and choose the menu option "Add". It will give the option to choose a file type.

#region

2011-06-06T11:23:00.000-07:00

#region is a preprocessor directive.Which is a block of code and it allows us to expand or collapse the code when using the outlining features of the MS visual studio code editor.
Syntax::
#region MyRegion

//your code here

#endregion

MyRegion is name you want to give to the region, which will appear in the visual studio code editor. A #region must be end with a #endregion.
#region do not affect the intermediate language output.

Shortcuts:

C# Preprocessor Directives

2011-06-05T02:09:00.000-07:00

Following are the c# preprocessor directives:

#if
#else
#elif
#endif
#define
#undef
#warning
#error
#line
#region
#endregion

MS visual Studio.net: Design Mode Split mode and Source Mode

2011-06-04T11:41:00.000-07:00

If you are developing a web application, you can switch between design mode split mode and source mode.When you are in source Mode, it will show HTML Tags and Asp.net code and you can manually edit it. You can switch to design mode by clicking the design button. In design mode you can see how your Asp.net page is going to look like when some one view your web page.Any change to source mode will be reflected in design mode and any change to design mode will be reflected to source Mode. Split mode will show both source mode and design mode together.
For windows form and web forms, you can see the file in design mode and source code associated with it. Double click on any form name in solution explorer will open it in design mode. Right click on any form and select the menu option "view code" to view the code associated with the form.

MS Visual Studeo.net: Toolbox

2011-06-01T11:36:00.001-07:00

Toolbox provides all the drag-drop controls for your application. If you are developing the web application, toolbox will show Asp.net controls and if you are developing a windows application it will show windows controls like Radio button, text box, button etc.
You can drag-drop any controls from the toolbox to your form. After drag and drop any controls, double click on the control to go the default event associated with the control.
Toolbox will be enabled only when you have a web form or win Form opened in design mode and is usually located on top left corner of the visual Studio.net.
By default, toolbox will be displayed as minimized(shown in following image by A). We will see only small icon written vertically with "Toolbox" on the left bar of VS.net. You can click on this minimized window to expand it(expanded window is marked as "C" in image). When you move the mouse away from it, it will automatically minimize.you can keep the the toolbox always expended by pressing the push-pin (marked as "B" in image)

Microsoft Visual Studio

2011-05-29T13:36:00.000-07:00

MS Visual Studio is an editor, Provided by microsoft to developers to write .net program easily. Visual Studio.net automatically generates lot of code, allows developers to drag and drop controls to a form, provides short cuts to compile and build the application.

Features of Visual Studio.Net :

Visual Studio.net automates the step required to compile the source code.
Visual Studio editor can detect errors and suggests code as appropriate as you required.
The visual studio designer for windows form and web form application allowing simple drag and drop design of user interface elements.
The visual studio contains many powerful tools for visualizing & navigating through the elements our projects, whether they are c# code files or other resource such as bitmap images or sound files.
The visual studio enables advance debugging techniques when developing projects, such as ability to step through code one instruction at a time while keeping an eye on the state of our applications.

Shortcut to open Microsoft Visual studio

2011-05-25T22:18:00.000-07:00

Shortcut to open Microsoft Visual studio
->start
->run
->type "devenv"
-> press ok
Now, Microsoft Visual studio will be open.

Publish your web application using visual studio .net

2011-05-15T22:31:00.000-07:00

Publishing the web application provides a measure of protection for your intellectual property and makes it more difficult for others to access the source code of your site. When you published your web application, then every .cs file convert into dll and .aspx file that are using these files automatically got reference to these dll. You can publish your web application to a local or shared folder, to an FTP site, or to a Web site that you access by using a URL.
To publish a Web application

In the Build menu, click Publish ProjectName.

OR
Right Click on web application in Solution explorer.
Click the ellipsis button (…) to browse to the location that you want to publish the Web application to.
Select the Replace matching files with local copies check box or the Delete all existing files prior to publish check box.
Select how you want to copy the Web application project files to the new location by using Only files needed to run this application, All project files, or All files in the source project folder.
You can include files from the App_Data folder by selecting the corresponding check box.
Click OK to publish the Web application project.
In the task bar, Publish succeeded is displayed when publishing has finished.

Benfits of Metadata

2011-05-09T09:41:00.000-07:00

Metadata allows .net languages to describes themselves automatically in a language natural manner, unseen by both the developer and the user. Metadata provides the following major benefits:
Self-describing type:- Comman language run-time modules and assemblies are self describing. The matadata contains everything needed to intract with another modules. Run-time modules and assemblies do not even require registration with the operating System.
Language interoperability and Easier component based design:- Metadata provides all the information required about compiled code for you to inherit a class from a PE filewritten in different language. We can create an instanse of any class written in any managed language(any language that target the CLR) without worrying about explicit marshaling or using custom interoperability code
attributes:- The .netframework allows you to declare a specific kinds of metadata, called attributes, in your compiled file. Attributes can be found throughout the .netframwork and are used to control in more detail how your programe behaves at run-time. Additinally you can emit your own custom metadata into .net framework files user defined custom attributes.

Source Code to send simple e-mail in asp.net

2011-03-28T14:23:00.000-07:00

Create user interface for sending the mail.
email.aspx page

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="email.aspx.cs" Inherits="email" %>
<html>
<head runat="server">
    <title>E-mail sending program</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <table width="100%" border="2">
    <tr>
        <td style="height: 40px; width: 55px;">
                 <asp:Label ID="Label3" runat="server" Text="From"></asp:Label></td>
        <td style="height: 40px"><asp:TextBox ID="TextBox1" runat="server"></asp:TextBox></td>
        </tr>
        <tr>
             <td>
                  <asp:Label ID="Label1" runat="server" Text="TO"></asp:Label></td>
             <td>
            <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox></td>
        </tr>
        <tr>
                <td style="height: 28px">
            <asp:Label ID="Label2" runat="server" Text="Subject"></asp:Label></td>
        <td style="height: 28px">
             <asp:TextBox ID="TextBox3" runat="server" ></asp:TextBox></td>
        </tr>
        <tr>
            <td style="height: 54px">
            </td>
            <td style="height: 54px">
                 <asp:TextBox ID="TextBox4" runat="server" Height="56px" TextMode="MultiLine"></asp:TextBox></td>
        </tr>
        <tr>
        <td></td>
        <td>
        <asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click" />
            <asp:Label ID="Label4" runat="server" Text="Label"></asp:Label></td></tr>
        </table></div>
    </form>
</body>
</html>
Its design view will be :

Code behind page:
email.aspx.cs page
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Net;
using System.Net.Mail;
public partial class email : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        MailMessage m = new MailMessage(TextBox1.Text, TextBox2.Text, TextBox3.Text, TextBox4.Text);
        try
        {
            NetworkCredential n = new NetworkCredential("yourEmailId","YourPassword");
            SmtpClient s = new SmtpClient("smtp.gmail.com", 587);
            s.EnableSsl = true;
            s.UseDefaultCredentials = false;
            s.Credentials = n;
            s.Send(m);
            Label4.Text = "send" ;
        }
        catch(Exception e1)
            {
                Label4.Text = "Enabled to send"+e1;
            }
    }
}

Here i am using gmail smtp server and its port. you can use own smtp server, If you have own smtp server.

Benefits of assembly

2011-02-23T13:14:00.000-08:00

Independence from system registry.
Solving versioning problem (DLL hell).

Download Cache

2011-02-01T12:55:00.000-08:00

It stores code downloaded from internet sites, isolated to the application to the application that triggered the download so that code downloaded on behalf of one application or page does not impact other applications.

Global assembly cache (GAC)

2011-02-01T12:49:00.000-08:00

It contains assemblies that are explicitly installed to be shared among applications on the computer. GAC is the special directory located in the windows \assembly directory (in windows XP) or WINNT\assembly directory (in windows 2000/2003). All shared assembly including the .net framework system assemblies supplied by Microsoft .net framework library are located and loaded in GAC.

Assembly Cache

2011-01-30T12:08:00.000-08:00

An assembly cache is a machine-wide code cache used for side by side storage of assemblies. There are two parts to the cache:

Global Assembly cache (GAC)
Download cache