MessageBox Class in Windows Form

MessageBox class is used to display informative messages to users. A message box can contains text, buttons and symbols. One cannot create a new instance of this class something like other classes. To display a message you need to call show() method of this class. It is a static method and accepts text, title, buttons, icons and etc. as per desired parameters.


To show a simple message to the user:
MessageBox.Show("This is My First Message");

And it will provide a message box as in following image

Show method have some overloads, we will use a standard overload that is mostly used in programming.

MessageBox.Show("This is My First Message","Title",
MessageBoxButtons.OKCancel,MessageBoxIcon.Information);

A message box will show like the following image.

In the above show method the first parameter is text to be shown, second parameter is the captions or title of the box, third parameter is the messageBox buttons (here OkCancel) and fourth parameter is the icon(here information icon) to be shown. There are some more buttons and icons to be used in this method which are:

MessageBox buttons which are in enumeration MessageBoxButtons

• AbortRetryIgnore: contains Abort, Retry and Ignore button.
• Ok: contains ok button.
• OkCancel: contains Ok and Cancel button.
• RetryCancel: contains Retry and Cancel button.
• YesNo: contain Yes and No buttons.
• YesNoCancel: contains Yes, No and Cancel buttons.

Message box icons which are in enumeration MessageBoxIcons

• Asterisk: symbol consisting a letter ‘l’ within a circle.
• Error: symbol consisting a letter ‘X’ within a white circle and red background.
• Exclamation: symbol consisting an exclamation mark within a rectangle.
• Hand: symbol consisting a white ‘X’ within a circle.
• Information: symbol consisting a letter ‘i’ within a circle.
• None: contains no symbol.
• Question: symbol consisting a question mark within a circle.
• Stop: symbol consisting a white X within a circle.
• Warning: symbol consisting a exclamation point within a triangle.

Here are some more overloads of Show() method.

MessageBox.Show("Text");

MessageBox.Show("Text", "Title");

MessageBox.Show("Text", "Title", MessageBoxButtons.OK);

MessageBox.Show("This is My First Message", "Title", MessageBoxButtons.OKCancel, MessageBoxIcon.Error);

We can set default button of the box, enable options of message box, enable of disable help button and etc.as per our requirements.

Status Strip Control
Error Provider Control

Restrict users from Entering in TextBox

Masked textbox supports a declarative syntax for accepting or rejecting user input. Masked textbox may be used to specify input characters, input position in the mask, mask literals and some more operations can also be done using masked textbox without any custom validation logic.

Textbox is used to allow the user to input text information to be used by the programmer. To use our custom logic we can restrict numbers/characters to be inputted by the user. We can restrict any key to be inputted by the user.

Textbox’s Key Press event occurs when the control has focus and user press and releases a key. It has following format that is in C# language:

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
}

The parameter e provides the data for this event which is of type KeyPressEventArgs. Char class has some in-built functions for checking the pressed and released key by user.

char.IsDigit(): whether the character is decimal digit or not.
char.IsLetter(): whether the character is a letter.
Char.IsLetterOrDigit(): whether the character is letter or digit.

There are many more method to check each type of data, we can read more here.
To restrict the user from entering the digit in textbox

if (char.IsDigit(e.KeyChar))
e.Handled = true;

Here e.Handled will tell the debugger that I have handled this event. We can use desired method to prevent specified type of key by the user.

To restrict both the letter and digit to be inputted by the user in c# language:

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (char.IsLetterOrDigit(e.KeyChar) || char.IsDigit(e.KeyChar))
e.Handled = true;
}

Now when we run this form and try to enter anything between a-z, A-Z and 0-9, we can’t enter anything among these values.

ASP.NET : how to Add control dynamically

The PlaceHolder Control
The PlaceHolder control is used as a container to store server controls that are added to the Web page at runtime. The PlaceHolder control does not produce any visible output and is used only as a container for other controls on the Web page.

Example of PlaceHolder control

 

<%@ Page Language="C#" %>
<!DOCTYPE html>
<script runat="server">
    protected void Button1_Click(object sender, EventArgs e)
    {
        TextBox text = new TextBox();
        text.Text = "This is the runtime textbox";
        text.Style["width"] = "300px";
        PlaceHolder1.Controls.Add(text);       
           
    }
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:Button ID="Button1" runat="server" Text="Click to add TextBox" OnClick="Button1_Click" />
        <br />
        <br />
        <br/>
        <asp:PlaceHolder ID="PlaceHolder1" runat="server"></asp:PlaceHolder>
    </div>
    </form>
</body>
</html>

Output

WPF: Alignments of Elements

In earlier post we have learnt about size-related properties i.e. Height & Width and Margin & Padding. In this article we will focus on alignments of elements. How a children should be positioned within a parent’s allocated space, is described by Alignment properties of an element.

There are two alignments i.e. Horizontal and Vertical and each one has its individual four values to be assigned.

Horizontal Alignment—Left, Center, Right and Stretch
Vertical Alignment—Top, Center, Bottom and Stretch

Each of these alignments have its own layout which is described below:

Left—Children are aligned to the left of parent’s allocated space.
Right—Children are aligned to the right of parent’s allocated space.
Top—Children are aligned to the top of parent’s allocated space.
Bottom—Children are aligned to the bottom of parent’s allocated space.
Center—Children are aligned to the center of parent’s allocated space.
Stretch—Children are stretched to fill the parent’s allocated space. Default value for alignments.

Place some buttons on a window and use above properties one by one and look out the effects of these alignments.

<Grid>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<StackPanel Grid.Row="0">
<Button HorizontalAlignment="Left">Button 1</Button>
<Button HorizontalAlignment="Center">Button 2</Button>
<Button HorizontalAlignment="Right">Button 3</Button>
<Button HorizontalAlignment="Stretch">Button 3</Button>
</StackPanel>
<StackPanel Grid.Row="1" Orientation="Horizontal">
<Button VerticalAlignment="Top" >Button 1</Button>
<Button VerticalAlignment="Center" >Button 2</Button>
<Button VerticalAlignment="Bottom" >Button 3</Button>
<Button VerticalAlignment="Stretch">Button 3</Button>
</StackPanel>
</Grid>

The preceding code yields a layout similar to the following screenshot. Positioning effects of both the alignments are visible.

Margin and Padding of Elements: WPF

In our previous post we have set Height and Width properties of an element, now we will set the next size related properties i.e. Margin and Padding. Margin controls how much extra space gets placed around the outside edges of the element, whereas padding controls around the inside edges of the element.

Margin and Padding can be assign in following simple ways:

• Margin = "10", same margin of all four sides.
• Margin = "10,5", 10 for left & right, 5 for top & bottom.
• Margin = "10,5,10,5", for left, top, right and bottom respectively.

Same can be used for padding. Here is xaml code with three buttons having some margins.

<StackPanel Orientation="Horizontal">
<Button Margin="10">Button 1</Button>
<Button Margin="20,5">Button 2</Button>
<Button Margin="20,15,20,15">Button 3</Button>
</StackPanel>

As padding controls around the inside edges of the element, I have used a border across each button:

<StackPanel Orientation="Horizontal" Height="60">
<Border Background="Aqua" BorderThickness="2">
<Button Padding="10">Button 1</Button>
</Border>
<Border Background="Aqua">
<Button Padding="10,15">Button 2</Button>
</Border>
<Border Background="Aqua">
<Button Padding="20,15,20,15">Button 3</Button>
</Border>
</StackPanel>

The effect of padding will look like in the following screenshot:

Varying the values of these margins and paddings, we can measure the changes. If one want to use all these margins through code behind then we have to use Thickness class like the below code:

Button button1 = new Button();
button1.Margin = new Thickness(10);
button1.Margin = new Thickness(20, 15, 20, 15);

As we can see that either we can use a single value or all the four values to use margin property of an element. There is no option to use the second type i.e. the one for left & right and one for top & bottom.

Alignments and Height & Width

ASP.NET: How to use Generic Handlers

Example of Generic Handlers
Step-1 : Add new "GenericHandlers.ashx" file in your project
 

<%@ WebHandler Language="C#" Class="Handler" %>

using System;

using System.Web;

public class Handler : IHttpHandler {



public void ProcessRequest (HttpContext context) {

context.Response.ContentType = "html";



context.Response.Write("Hello World");


manaeform(context);





}
public void manaeform(HttpContext context)


{
context.Response.Write("<html><body><form>");

context.Response.Write("<h2>Select your feature</h2>");

if (context .Request .Params ["Feature"]==null)


{
context.Response.Write("<select name='Feature'>");

context.Response.Write("<option>asp.net </option>");

context.Response.Write("<option>java </option>");
context.Response.Write("</select></form></body></html>");


}

}


public bool IsReusable {

get {

return false;


}

}

} 

Output

How to set Height and Width of Elements: WPF

Panels, also called parent elements, supports multiple child elements to be arranged in it. Parents decide about where to render and how much space the children get. WPF elements tend to size to their content that is to be done through its SIzeToContent property.

Height & Width:

There are several properties which are used for layouts of an element, some are size related and some are position related. Size related properties includes height, width, margin and padding. Position related properties includes horizontal & vertical alignment.

All the elements have height and width properties and also they have MinHeight, MinWidth, MaxHeight, MaxWidth to specify the values. Height/Width property is used to get or set the suggested height/width of the respective element.

We can create a textblock with height(100) and width(200) using the below xaml code.

<TextBlock Text="Hello World" Height="100" Width="200" Background="Black"/>

The above code may be written like the below code as we have discussed in our “earlier post”.

<TextBlock>
<TextBlock.Text>Hello World</TextBlock.Text>
<TextBlock.Height>100</TextBlock.Height>
<TextBlock.Width>200</TextBlock.Width>
<TextBlock.Background>Black</TextBlock.Background>
</TextBlock>

The textblock looks like as the following screenshot:

Element also contains some more size-related properties like DesiredSize, RenderSize, ActualHeight and ActualWidth. RenderSize represents the final size of an element, and ActualWidth and ActualHeight are exactly same as the final width and final height of an element. DesiredSize is used when IsMeasureValid property is true for an element.

Alignments and Margin & Padding