Improve ASP.Net Performance by effective utilitzation of String

Many people ask me that how they can improve their website's performance? There are many ways through which you can improve the performance of your website but today, I will discuss the performance improvement with Strings.
In my opinion String is the most frequently used data type compared to other data types available. But there is a big problem with string, it is immutable. An immutable object is an object which cannot be modified. So whenever we try to change anything with string a new string object is created. These frequent creations of objects degrade the system's policy.

Avoid using "" as empty string

Every time when you write "" a new string object is created. But if you use string.Empty it will not create any additional string before assignment.
//bad practice
string str = "";

//good practice
string str1 = string.Empty;

Avoid .ToLower()/.ToUpper() for Comparison

Usually developers heavily use .ToLower() or .ToUpper() to perform case insensitive comparison. Instead you should use string.Compare function.
//Bad Practice
string errorCode= "ec-1001";
if (errorCode.ToLower() == "ec-1001")


//good Practice
string errorCode1 = "ec-1001";
if (string.Compare( errorCode1,"ec-1001",true)==0)

Also there are situations when we can control the case of a string i.e. generally we add 'M' or 'F' for gender. Now we can ensure that throughout application we either use capital 'M' or small 'm' to define male. A good approach is to use const in such cases.
const string Male = "M";
const string Female = "F";
string myGender = Male;

Avoid multiple string concatenation

Whenever you have to modify a string many times then consider using StringBuilder instead of simple string. Every time when you modify a string, a new object would be created. However, StringBuilder is mutable object and it performs string modifications without creating multiple objects.

//Bad practice
string text = "start";
text += "start 1";
text += "start 2";
text += "start 3";
text += "start 4";
text += "start 5";

for (int i = 0; i < 10; i++)
    text += "text " + i;

//Good Practice
StringBuilder sb = new StringBuilder();
sb.Append("start 2");
sb.Append("start 3");
sb.Append("start 4");
sb.Append("start 5");

for (int j = 0; j < 10; j++)
    sb.Append( "text " + j);

Drag and Drop in Siliverlight using Mouse

Recently I started working with Silverlight. It is really a wonderful tool from Microsoft and I am too excited about it. It gives developer the power to create impressive looking user interface. In this tutorial I will focus on drag and drop functionality in Silverlight using mouse. You can download complete source code from

First create a new Silverlight Application project, here is how your project will look like:-

I have added event handlers for MouseLeftButtonDown,MouseLeftButtonUp,MouseMove and LostMouseCapture. I also added a canvax and a button in MainPage.xaml. Here is the code of MainPage.xaml after adding events:-

<UserControl x:Class="SliverLightMouseEvents.MainPage"
    d:DesignHeight="300" d:DesignWidth="491" 

    <Canvas x:Name="mainCanvas" Width="640" Height="480" >
        <Button Content="AddRectangle" Width="100" Height="30" Margin="12,258,378,12" Click="Button_Click" />

On the button click I have added a rectangle to mainCanvas. Here is how it is done:-

private void Button_Click(object sender, RoutedEventArgs e)
    //Creating a rectangle
    Rectangle rectangle = new Rectangle()
        Stroke = new SolidColorBrush(Colors.Black),
        Width = 100,
        Height = 100,
        Fill = new SolidColorBrush { Color = Color.FromArgb(200, 146, 5, 23) }

    //Set its initial position
    Canvas.SetLeft(rectangle, 100);
    Canvas.SetTop(rectangle, 100);

    //Adding it to mainCanvas

Now first we have to handle MouseLeftButtonDown event. Here is the code:-

private void UserControl_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    //If mouse button is down and control on which button is pressed is rectangle
    if (e.OriginalSource.GetType() == typeof(Rectangle))
        this.isMoving = true;

        //Calculate the current mouse's relative position
        clickOffset.X = e.GetPosition(mainCanvas).X - Canvas.GetLeft((Rectangle)e.OriginalSource);
        clickOffset.Y = e.GetPosition(mainCanvas).Y - Canvas.GetTop((Rectangle)e.OriginalSource);

        //Generate Mouse Events even if mouse is moved outside control's area

One thing which you should remember when doing drag and drop is CaptureMouse() function. Many user will move their mouse outside your application while draging and if you do not write CaptureMouse() when mouse is outside you will recieve no events from mouse.

Now here is the code which I wrote in MouseMove event:-
private void UserControl_MouseMove(object sender, MouseEventArgs e)
    if (this.isMoving) //If mouse button is down
        if (e.OriginalSource is Rectangle) //if control is rectangle
            Rectangle rect = e.OriginalSource as Rectangle; //Get the original control

            //Changing its color so we can get the feel of selection
            rect.Fill = new SolidColorBrush { Color = Color.FromArgb(100, 146, 5, 23) };

            //Calculate the distance form initial mouse down and adjust top,left accordingly
            Canvas.SetLeft(rect, e.GetPosition(mainCanvas).X - clickOffset.X);
            Canvas.SetTop(rect, e.GetPosition(mainCanvas).Y - clickOffset.Y);

In above code, I adjusted the top,left of the Rectangle as per position of mouse.

Now when user release the mouse button, MouseLeftButtonUp event is fired. Here is the code which I written in MouseLeftButtonUp event:-

private void UserControl_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
    //if mouse is moving
    if (this.isMoving)
        //if control is rectangle on which mouse is moving
        if (e.OriginalSource is Rectangle)
            //Change rectangle color back to normal
            Rectangle rect = e.OriginalSource as Rectangle;
            rect.Fill = new SolidColorBrush { Color = Color.FromArgb(200, 146, 5, 23) };
        //Set moving to false
        this.isMoving = false;

        //Stop listening mouse events which are outside current control's boundary

Finally here is the code of LostMouseCapture event, if you remove this code from my sample, it will behave weired when mouse goes outside control's area:-

private void UserControl_LostMouseCapture(object sender, MouseEventArgs e)
    if (this.isMoving)// if Previously mouse is clicked down
        this.isMoving = false; //mark that mouse is now moved up

Finally here is the output of the application:-