Getting byte array from an image.

private static byte[] ConvertImageToByteArray(System.Drawing.Image imageToConvert,ImageFormat formatOfImage)
{
byte[] Ret;
try
{

using (MemoryStream ms = new MemoryStream())
{
imageToConvert.Save(ms, formatOfImage);
Ret = ms.ToArray();
}
}
catch (Exception) { throw; }

return Ret;
}

...S.VinothkumaR.

Boxing And UnBoxing

Boxing and Unboxing are two important portions of .NET technology. Boxing is nothing but converting a value type object to a reference type object. Unboxing is completely explicit.

Now let us get an idea regarding reference type and value type objects. We all know that a new operator returns the memory address of an object that is allocated from the managed memory (a pool of memory). We usually store this address in a variable for our convenience. These types of variables are known as reference variables. However, the value type variables are not supposed to have the references; they always used to have the object itself and not the reference to it.

Now if we consider the statement written above in Listing 3, the C# compiler will detect System.Int32 as a value type and the object is not allocated from the memory heap, assuming this as an unmanaged one.

In a general way we should declare a type as a value type if the following are true.

1. The type should be a primitive type.
2. The type does not need to be inherited from any other types available.
3. No other types should also be derived from it.

This example shows how an integer type is converted to a reference type using the boxing and then unboxed from the object type to the integer type.

class Test
{
static void Main()
{
int i = 1; // i is an integer. It is a value type variable.
object o = i;
// boxing is happening. The integer type is parsed to //object type
int j = (int)o;
// unboxing is happening. The object type is unboxed to //the value type
}
}

Leap Year checking in Javascript

Hi all,

Here is I'm going to check the given year is leap or not...How to do....check it out..

I don't state that this code is perfect but it does work.

Just copy and paste the following function in to script tag inside the header tag so that it can be called from anywhere in this HTML document.


function isleap()
{
var yr=document.getElementById("year").value;
if ((parseInt(yr)%4) == 0)
{
if (parseInt(yr)%100 == 0)
{
if (parseInt(yr)%400 != 0)
{
alert("Not Leap");
return "false";
}
if (parseInt(yr)%400 == 0)
{
alert("Leap");
return "true";
}
}
if (parseInt(yr)%100 != 0)
{
alert("Leap");
return "true";
}
}
if ((parseInt(yr)%4) != 0)
{
alert("Not Leap");
return "false";
}
}

Basically this code gives the rules to check if a year is a leap year. If the year is no divisible by 4 then it is not a leap year. If the year is divisible by 100 but not by 400 then it is not a leap year. Otherwise the remaining options leave us with a leap year so I hard coded what to do. The Reason I have coded in what to do otherwise is to highlight the two different statements of verifying that something does match and verifying something does not match.

Just call this script function where you want...as follows,


onclick="isleap()"

that's it....

...S.VinothkumaR.

Caching in ASP.NET 2.0

Here is the different kind of caching that you can use in your web applications:

· Output Caching

· Fragment Caching

· Data Caching

· Cache Configuration

Output Caching

Performance is improved in an ASP.NET application by caching the rendered markup and serving the cached version of the markup until the cache expires. For example, if you have a page that displays user information from a database, caching will help improve performance by serving the page from memory instead of making a connection to the database on each page request.

You can cache a page by using the OutputCache API or simply by using the @OutputCache directive.

<%@ Page Language=”C#” %>

<%@ OutputCache Duration=”15” VaryByParam=”none” %>

The above cache directive will cache the page for 15 minutes.

So output caching is great for when you want to cache an entire page.

Fragment Caching

In many situations caching the entire page just isn’t going to cut it, for some reason or another you require specific sections of the page to display live information. One way to improve performance is to analyze your page and identify objects that require a substantial overhead to run. You can build a list of these objects that are expensive to run, and then cache them for a period of time using fragment caching.

For example, say your page default.aspx consists of three user controls. After looking over the code, you identified that you can cache one of them. You can simply add the caching directive to the top of the user control:

<%@ Control %>

<%@ OutputCache Duration=”5” VaryByParam=”none” %>

Now keep in mind that the actual page that contains the control is not cached, only the user control. This means that the default.aspx page will be rendered each and every page request, but the user control is only ‘run’ every 15 minutes.

Data Caching

So we know that we can cache an entire page, or a fragment of a page by caching down to the user control level. Wouldn’t it be great if we could cache down to the object level? The good news is you can with ASP.NET Data caching.

The cache consists of a dictionary collection that is private to each application in memory. To insert items in the cache simply provide the collection with a unique name:

Cache[“someKey”] = myObject;

Retrieving the object form the cache:

myObject = (MyObject)Cache[“someKey”];

It is a good time to point out that you should always remember to check for null, and be sure to caste to your datatype.

Cache Configuration

If you are familiar with how caching worked in ASP.NET 1.0, you realize that managing all the cache directions for all your pages could potentially get out of hand. ASP.NET 2.0 introduces Cache Profiles that helps you centrally manage your cache. Cache settings can be inherited by your pages, and overridden if required by using the OutputCache directive.

The page directive looks pretty much the same, expect this time it references a cache profile that you defined in your web.config file.

So each and every page that references the ‘myCacheProfile1’ can be centrally managed in the web.config, this means that any changes to the cache settings in the web.config file will be automatically changed on all your referenced pages.

...S.VinothkumaR.

ASP.Net page life cycle

Here is I’m going to explain, behind the scenes when a ASP.NET page loads.

In general, the life cycle of a ASP.NET page comprises of a series of steps like initialization, instantiation of controls, state management, the firing of event handler code, and the final stage of rendering.

The following are the various stages a page goes through:

Page Request

The request page is either parsed or compiled, or fetched from the cache.

Start

Page properties like the Request and Response are set. The type of request is determined, specifically whether it is a new Request or it is a PostBack. Culturing properties are also determined via the pages ICulture property.

Page Initialization

All the controls on the given page are initialized with a UniqueID (please don’t confused this with the ID property as the UnqiueID is a unique, hierarchicial identifier which includes the server control’s naming container). Theming is also applied at this stage.

Load

If the current request is a PostBack, the data from the viewstate and control state is loaded to the appropriate properties of the controls.

Validation

The Validate method of all the validator controls are fired, which in turn sets the Boolean property IsValid of the controls.

Postback Event Handling

If the current request is a PostBack, all event handlers are called.

Rendering

ViewState data is saved for all the controls that have enabled viewstate. The Render method for all the controls is fired which writes its output to the OutputStream via a text writer.

Unload

Once the page has been rendered and sent, the Page’s properties are unloaded (cleanup time).

So know you have a better understanding of the various stages of a ASP.NET pages life cycle, you should be aware that within each of the above stages there are events that you can hook into so that your code is fired at the exact time that you want it to.

Event Wire-up is another important concept to understand. So Event wire-up is where ASP.NET looks for methods that match a naming convention (e.g. Page_Load, Page_Init, etc) , and these methods are automatically fired at the appropriate event. There is a page level attribute AutoEventWireup that can be set to either true or false to enable this behaviour.

Below are some of the more popular events that you should understand as you will most likely be interested in them:

PreInit

You can use this event to:

· Create /recreate dynamic controls

· Set a master page or theme dynamically

· Access profile properties

Init

Used to read or initialize your control properties.

InitComplete

Used when you need to access your properties after they have been initialized.

PreLoad

Used when you need to process things before the Load event has been fired.

Load

The Page’s OnLoad method and all of its child control’s OnLoad method are fired recursively. This event is used to set properties and make database connections

Control Events

Control specific events are handled at this stage. e.g. Click event’s for the button control.

LoadComplete

This stage is for when you need to access controls that have been properly loaded.

PreRender

Can be used to make any ‘last chance’ changes to the controls before they are rendered.

SaveStateComplete

This event is used for things that require view state to be saved, yet not making any changes to the controls themselves.

Render

The page object calls this method on all of the controls, so all the controls are written and sent to the browser.

Unload

All the controls UnLoad method are fired, followed by the pages UnLoad event (bottom-up). This stage is used for closing database connections, closing open files, etc.

It is import to understand that each server control has its very own life cycle, but they are fired recursively so things may not occur at the time you think they do (they occur in reverse order!). What this means is that some events fire from the bottom up like the Init event, while others load from the top-down like the Load event.


...S.VinothkumaR.

LogOut Effect in IE, FireFox and OPERA

The following script will help you to do the effect when you click the logout button .

Copy and paste the following script in to your head section and call the log_out() in button click.



...S.VinothkumaR.

DataTable in C#

Here is the sample code for creating and assigning values in to a datatable and set to datagrid via coding….

DataTable dt = new DataTable();

dt.Columns.Add("S.No", typeof(string));

dt.Columns.Add("UserID",typeof(string));

dt.Columns.Add("FamilyId",typeof(string));

dt.Columns.Add("PhotoGalleryId",typeof(string));

dt.Columns.Add("FileName",typeof(string));

dt.Columns.Add("Status", typeof(string));

dt.Columns.Add("Success", typeof(string));

dt.Columns.Add("ImagePath", typeof(string));

DataRow Dr;

command=new SqlCommand("select * from [Assets]",connection);

connection.Open();

SqlDataReader reader = command.ExecuteReader();

int i = 1;

while(reader.Read())

{

Dr=dt.NewRow();

Dr[0] = i.ToString();

Dr[1] = reader.GetValue(1);

Dr[2] = reader.GetValue(2);

Dr[3] = reader.GetValue(3);

Dr[4] = reader.GetValue(4);

Dr[5] = reader.GetValue(5);

Dr[6] = reader.GetValue(7);

Dr[7] = ConfigurationManager.AppSettings["OrgImgAnchor"];

dt.Rows.Add(Dr);

i += 1;

}

grdStatus.DataSource = dt;

grdStatus.DataBind();

connection.Close();

...S.VinothkumaR.