Developers Field: 2013

Wednesday, 28 August 2013

Enumerations

C# provides all the data types that are available in Java, and adds support for unsigned numerals and a new 128-bit high-precision floating-point type.

For each primitive data type in Java, the core class library provides a wrapper class that represents it as a Java object. For example, the Int32 class wraps theint data type, and the Double class wraps the double data type.

On the other hand, all primitive data types in C# are objects in the System namespace. For each data type, a short name, or alias, is provided. For instance,int is the short name for System.Int32 and double is the short form of System.Double.

The list of C# data types and their aliases is provided in the following table. As you can see, the first eight of these correspond to the primitive types available in Java. Note, however, that Java's boolean is called bool in C#.

Short Name	.NET Class	Type	Width	Range (bits)
byte	Byte	Unsigned integer	8	0 to 255
sbyte	SByte	Signed integer	8	-128 to 127
int	Int32	Signed integer	32	-2,147,483,648 to 2,147,483,647
uint	UInt32	Unsigned integer	32	0 to 4294967295
short	Int16	Signed integer	16	-32,768 to 32,767
ushort	UInt16	Unsigned integer	16	0 to 65535
long	Int64	Signed integer	64	-9223372036854775808 to 9223372036854775807
ulong	UInt64	Unsigned integer	64	0 to 18446744073709551615
float	Single	Single-precision floating point type	32	-3.402823e38 to 3.402823e38
double	Double	Double-precision floating point type	64	-1.79769313486232e308 to 1.79769313486232e308
char	Char	A single Unicode character	16	Unicode symbols used in text
bool	Boolean	Logical Boolean type	8	True or false
object	Object	Base type of all other types
string	String	A sequence of characters
decimal	Decimal	Precise fractional or integral type that can represent decimal numbers with 29 significant digits	128	±1.0 × 10e−28 to ±7.9 × 10e28

Because C# represents all primitive data types as objects, it is possible to call an object method on a primitive data type. For example:

static void Main()
{
    int i = 10;
    object o = i;
    System.Console.WriteLine(o.ToString());
}

This is achieved with the help of automatic boxing and unboxing. For more information, see Boxing and Unboxing (C# Programming Guide).

Constants

Both Java and C# provide the ability to declare a variable whose value is specified at compile time and cannot be changed at runtime. Java uses the final field modifier to declare such a variable, while C# uses the const keyword. In addition to const, C# provides the readonly keyword to declare variables that can be assigned a value once at runtime--either in the declaration statement or else in the constructor. After initialization, the value of a readonly variable cannot change. One scenario in which readonly variables are useful is when modules that have been compiled separately need to share data such as a version number. If module A is updated and recompiled with a new version number, module B can be initialized with that new constant value without having to be recompiled.

Enumerations

Enumerations, or enums, are used to group named constants similar to how they are used in C and C++; they are available in Java beginning in Version 1.5. In C#, enums are value types, and enum constants must be integral numeric values. The ToString method can be used to print out string representations of the named constants. The following example defines a simple Color enumeration in C#.

public enum Color
{
    Green,   //defaults to 0
    Orange,  //defaults to 1
    Red,     //defaults to 2
    Blue     //defaults to 3
}

Integral values can also be assigned to enumerations as shown in the following enum declaration:

public enum Color2
{
    Green = 10,
    Orange = 20,
    Red = 30,
    Blue = 40
}

The following code example calls the GetNames method of the Enum type to display the available constants for an enumeration. It then assigns a value to an enumeration and displays the value.

class TestEnums
{
    static void Main()
    {
        System.Console.WriteLine("Possible color choices: ");

        //Enum.GetNames returns a string array of named constants for the enum. 
        foreach(string s in System.Enum.GetNames(typeof(Color)))
        {
            System.Console.WriteLine(s);
        }

        Color favorite = Color.Blue;

        System.Console.WriteLine("Favorite Color is {0}", favorite);
        System.Console.WriteLine("Favorite Color value is {0}", (int) favorite);
    }
}

Beginning in C# 3.0, enumerations can be extended with user-defined extension methods. For more information, see How to: Create a New Method for an Enumeration (C# Programming Guide).

Output

Possible color choices:

Green

Orange

Red

Blue

Favorite Color is Blue

Favorite Color value is 3

Agile Methodology

Introduction

Waterfall model follows application development in phases with checkpoint and deliverable documents in each checkpoint. It advocates rigours project management, strategy and processes to track the status. The main drawback is that it requires more than 80% project understanding before kicking off the project which is impossible in major cases. Cause of volatile requirements and understanding business feels, 80% of software projects using this methodologyfail to meet their objectives.

Typical Waterfall Model

Agile Methodology

Agile mythology has small box iterations rather than phases. The output of each iteration will be production release deliverable and could be evaluated and get early feedback.

Agile was a significant departure from the heavyweight document-driven software development methodologies—such as waterfall—in general use at the time.

Agile refers to more collaboration and interaction between different departments at enterprise level and delivers the successful product with individual contribution.

Agile methodologies embrace iterations. Small teams work together with stakeholders to define quick prototypes, proof of concepts, or other visual means to describe the problem to be solved. The team defines the requirements for the iteration, develops the code, and defines and runs integrated test scripts, and the users verify the results. Verification occurs much earlier in the development process than it would with waterfall, allowing stakeholders to fine-tune requirements while they’re still relatively easy to change.

It promotes adaptive planning, evolutionary development & delivery, a time-boxed iterative approach, and encourages rapid and flexible response to change.

XP (Extreme Programming)

It advocates frequent “release” in short development cycles, each release follows with several iterations. When the product release has enough features to satisfy the user, the team terminates iteration cycle and releases the software.

Other elements of Extreme Programming include: programming in pairs, continuous integration, add only needed features for a particular release.

Users write a story which helps the team to estimate the time to build the release and to define acceptance testing. A user is a part of XP team and adds the detail requirement as the software is being built. This allows requirements to evolve as both users and developers define what the product will look like.

Continuous Integration: Integrate often at least once a day using automated continuous integration tool
Pair Programming: Pair programing to extensively code review while coding
Project velocity: Velocity is a measure of how much work is getting done on the project. This important metric drives release planning and schedule updates.

Scrum

Scrum is a way for teams to work together to develop a product wherein requirement changes rapidly during development. Product development, using Scrum, occurs in small pieces, with each piece building upon previously created pieces. Building products one small piece at a time encourages creativity and enables teams to respond to feedback and change, to build exactly and only what is needed. Unlike XP, Scrum methodology includes both managerial and development processes.

Sprints: Short development process
Stand up meeting: Daily 10 minutes meeting status of the work to be done that day, progress from the day before, and any blocks that must be cleared
Scrum Master: The ScrumMaster is the person responsible for managing the Scrum project
Sprint backlog: Sprint backlog is the list of backlog items assigned to a sprint, but not yet completed.
Burndown chart: This chart, updated every day, shows the work remaining within the sprint. The burn down chart is used both to track sprint progress and to decide when items must be removed from the sprint backlog and deferred to the next sprint.
Product backlog: Product backlog is the complete list of requirements

References

Tuesday, 2 July 2013

Define page life cycle events with example in ASP .Net

Here You will get the solution of following queries:

Ques: What is page life cycle in asp .Net?

Ques: Describe events used in complete asp .net page life cycle.

Ques: Specify phase used in asp .Net page life cycle

Ques: Define Init, Load, Render and Unload events in page life cycle.

I L R S U

I - Init
L-Load
R-Render
S-SaveState
U -Unload

Today I want to share some knowledge about ASP .Net. Every developer who is working on ASP .Net must know about the Page life cycle[first step of web development using .Net technology]. Some of our friends after having 2-3 years of ASP .Net experience still don't have proper knowledge about all the events used in Page Life Cycle . As a developer I always got confused about page life cycle events in my beginning days, Here I am describing all the events with examples wherever applicable.

PreInit

PreInit is the first phase in asp.net page life cycle events. This is the place where one can dynamically set their master page in the code. In such case you can also set any theme or skin to your page, in PreInit we can also set the properties of the server controls of Master page, like the code below:

protected void Page_PreInit(object sender, EventArgs e)

{

if (textBox1 == null)

{

Response.Write("Pre Init, server control Not available");

}

else

{

string TextinInit = textBox1.Text;

Response.Write("Pre Init, Server Control enabled");

}

Page.MasterPageFile = "~/TestInitMaster.master";

TextBox _mstTextBox = (TextBox)Page.Master.FindControl("txtMessage");

Label _mstLabel = (Label)Page.Master.FindControl("lblMessage");

_mstLabel.Text = "Setted in default page at time : " +ateTime.Now.ToString();

_mstTextBox.Text = "Textbox set in default page";

}

In above you can see I’ve used a master page dynamically and set a label and TextBox’s Text property of that master page in runtime that means we can set the master page dynamically and associate the values in their controls if any. If you try to set the masterpage in any other event after Page_PreInit event, you will get an error message that will tell you that the master page only can be set on or before Page_PreInit event. In Page_PreInit event you can also see at the top level I’m checking a TextBox1 value whether it’s null or not. It is a server control (TextBox), but in PreInit the value will always be null of this text box or any other server control. So if I want to conclude the thing, in Page_PreInit controls are not fully initialized. So use this event for setting MasterPage file in your code. Each control Unique ID’s are also available at this event.

Init

Init is called when you can initialize your page controls, this is the place that comes into picture after each Control initialization, till this event they get their Unique Id, master page etc. In Init you cannot access any controls properties after the last viewstate, I mean suppose you enter some text in a textbox control and click on a button control that makes a postback, now you want to view the value latest entered. In such case you will be able to see the textbox value which you’ve entered after the round trip happens, this is because of ViewState property of controls. That means they preserved your last saved value, but you see this value after Init phase because, usually we don’t use these events in our code and use just Page_Load event where the Viewstate value already got loaded. But as in Init phase, we cannot access our latest entered values in textbox, so in Init you won’t be able to get the latest changes. So I can say in Init we won’t be able to get the postback value.

InitComplete

In this event, Viewstate functionality is turned on for server control. Viewstate of controls allows preserving their values across postback.

PreLoad

This is the first event where viewstate functionality starts retrieving their values. PreLoad executes after InitComplete method. In this method, page has loaded values from viewstate. So for example in a button click event if you create a viewstate like below than what will going to be happen:

protected void btnSubmit_Click(object sender, EventArgs e)

{

ViewState["myData"] = "just a text string";

}

After button click, postback will happen at it will start calling page events like PreInit, Init, Initcomplete. Till these three events you will not be able to get the value of Viewstate “myData”. Even when the event fires PreLoad event of page, at this time you cannot access the ViewState, this is because ViewState will set the value when asp.net reaches the ButtonClick event, and this will happen after Load event, so one more time we will click on our submit button, and because now the ViewState[“myData”] resides into my page, I can access it on my PreLoad event. For better understanding please see the screen shot below:

Load

Most of the developers are familiar with the page load, as this is the only event that comes by default in aspx.cs page when you start doing anything with your code behind. The page Load events executes after the Page_PreLoad event. If you have created your own Load method in constructor of your code behing, then this will be the method that will execute before the Page_Load event and after Page_PreLoad event, for better understanding refer to the image below:

As you are seeing in above code, I’ve created my own Page_Load event in my code behind as well as the default Load event, I didn’t mention Page_PreLoad event here, but it will execute after Page_InitComplete event. So back to the image, the _Default_Load will execute first before the Page_Load event. If you have any master page in your page, then the Load event of your master page will run followed by the user control Load event if they exist in your file.

Events

After the Page_load the next event is Page Control’s event. For example, if you have a control that raises postback just like button, and you clicked on the Button, so after Page_Load your Button_Click event will fire, and do the rest of the thing you’ve mentioned in your page. for better understanding please refer to the image below, event execution will be happen in that sequence how image is showing, in event portion whatever you will do that will go ahead and will do the things you’ve mentioned in you page. just like below, I said to create a ViewState[“myData”] and put some string inside that viewstate. So now the viewstate is ready to preserve ahead in my code.

In Events you can also check the Page.IsValid property if you’ve used any validator controls in your page like regularexpressionValidator, requiredFieldValidator, Range etc. To check this property refer to the image below.

LoadComplete

This event can be used when all the event processing has been done in the page.

PreRender/PreRenderComplete

PreRender event gets called when page has created all the controls that user will see in his browser. PreRenderComplete is the last place to change anything in the page. After this event any changes will not get preserved in page cycle.

SaveStateComplete

event gets fired immediately after the PreRenderComplete event, in this event the viewstate functionality and control state get saved, as I said in PreRenderComplete changes can be done that will affect the next postback. In SaveStateComplete you can do the changes in your server control, but the state won’t be available in next postbacks.

Render
Render is not an event but this is the phase where the HTML of your page will get rendered to the output stream with the help of HTMLTextWriter. You can override the Render method of page if you want to write your own code rather than the actual HTML text. As like below:

As you can see in the code above, I’ve override the Render method in my code and write something with Heading 1 tag and later on called the base.render method. In current scenario the thing will happen is: apart my server controls code in my browser I’ll be able to see my Hello world text also. If I remove the base.render method calls, than I won’t be able to view my any control if I’ve created in page.

Unload
This is the last event that gets fired. This is the page cleaning process like closing the open file connections etc, so in this process you cannot do any kind of manipulation with data that affect the rendering, you are restricted to use Response property also, and doing such you will get an exception message.

There might be some mistakes with this article but I tried my best to share with you, So if you have some queries OR suggestions please feel free and share the by comment. Thank you for reading this post..