Visual Basic –User Interface-III

Visual Basic –User Interface-IV

Govt. Polytechnic(W)

Faridabad

27th September 2016

Public Class Form1

Dim St, Mt1, MT2 As String

Dim Mb1, Mb2, Mt1ToolStripMenuItem, MT2ToolStripMenuItem As ToolStripMenuItem

Private Sub Add_Menu_Click(sender As Object, e As EventArgs) Handles Add_Menu.Click

Mt1 = TextBox2.Text MT2 = TextBox3.Text St = TextBox1.Text Dim Ab1, Ab2 As

ToolStripDropDownItem Mb1 = ColorToolStripMenuItem Mb2 = CalenderToolStripMenuItem Ab1 = Me.Mb2 Ab2 = Me.Mb1

Me.RunTimeOptionToolStripMenuItem.Name = St

Me.RunTimeOptionToolStripMenuItem.Size = New System.Drawing.Size(120, 22)

Me.RunTimeOptionToolStripMenuItem.Text = St

Me.RunTimeOptionToolStripMenuItem.DropDownItems.AddRange({Ab1, Ab2})

End Sub

CODE

Mt1 = TextBox2.Text

MT2 = TextBox3.Text

St = TextBox1.Text

Dim Ab1, Ab2 As ToolStripDropDownItem

Me.Mt1ToolStripMenuItem = New System.Windows.Forms.ToolStripMenuItem()

Me.Mt1ToolStripMenuItem.Name = Mt1

Me.Mt1ToolStripMenuItem.Size = New System.Drawing.Size(120, 22)

Me.Mt1ToolStripMenuItem.Text = Mt1

Me.MT2ToolStripMenuItem = New System.Windows.Forms.ToolStripMenuItem()

Me.MT2ToolStripMenuItem.Name = MT2

Me.MT2ToolStripMenuItem.Size = New System.Drawing.Size(120, 22)

Me.MT2ToolStripMenuItem.Text = MT2

Mb1 = Mt1ToolStripMenuItem

Mb2 = MT2ToolStripMenuItem

Ab1 = Me.Mb2

Ab2 = Me.Mb1

Me.RunTimeOptionToolStripMenuItem.Name = St

Me.RunTimeOptionToolStripMenuItem.Size = New System.Drawing.Size(120, 22)

Me.RunTimeOptionToolStripMenuItem.Text = St

Me.RunTimeOptionToolStripMenuItem.DropDownItems.AddRange({Ab1, Ab2})

End Sub

Code

Private Sub Start_Timer_Click(sender As Object, e As EventArgs) Handles Start_Timer.Click

TextBox1.Text = 0

Timer1.Start()

End Sub

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

Timer1.Stop()

TextBox1.Text = TextBox1.Text + Timer1.Interval

End Sub

Codes

Private Sub Add_Menu_Click(sender As Object, e As EventArgs) Handles Add_Menu.Click

Mt1 = TextBox2.Text MT2 = TextBox3.Text St = TextBox1.Text Me.Mt1ToolStripMenuItem = New

System.Windows.Forms.ToolStripMenuItem() Me.Mt1ToolStripMenuItem.Name = Mt1 Me.Mt1ToolStripMenuItem.Size = New

System.Drawing.Size(120, 22) Me.Mt1ToolStripMenuItem.Text = Mt1

Me.MT2ToolStripMenuItem = New System.Windows.Forms.ToolStripMenuItem()

'Friend WithEvents Mt1ToolStripMenuItem As ToolStripMenuItem

'Friend WithEvents MT2ToolStripMenuItem As ToolStripMenuItem

Me.MT2ToolStripMenuItem.Name = MT2 Me.MT2ToolStripMenuItem.Size = New

System.Drawing.Size(120, 22) Me.MT2ToolStripMenuItem.Text = MT2

Mb1 = Mt1ToolStripMenuItem Mb2 = MT2ToolStripMenuItem Ab1 = Me.Mb1 Ab2 = Me.Mb2 Me.RunTimeOptionToolStripMenuItem.Name = St Me.RunTimeOptionToolStripMenuItem.Size = New

System.Drawing.Size(120, 22) Me.RunTimeOptionToolStripMenuItem.Text = St

Me.RunTimeOptionToolStripMenuItem.DropDownItems.AddRange({Ab1, Ab2})

End Sub

Private Sub Mt1ToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles Mt1ToolStripMenuItem.Click

MsgBox("Menu Item 1" & " " & Mt1ToolStripMenuItem.Text)

End Sub

Private Sub MT2ToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles MT2ToolStripMenuItem.Click

MsgBox("Menu Item 2" & " " & MT2ToolStripMenuItem.Text)

End Sub

Masked TextBox

.NET framework offers a myriad of languages which puts us programmers into a deepthought process about which programming language best suits our needs.

A variable is a named memory location. They are programming elements that can change during program execution.

Data that needs to be stored in memory & accessed at a later time are stored in variables.

All the primitive types such as int, double etcare value type variables.

The simple types basically consist of Boolean and Numeric types, where Numeric is further divided into Integral and Floating Point.

Object type or reference type variables are those, which are allocated storage space in the heap.

Reference type objects can be null. When a reference type is allocated under the covers a value is allocated on the heap and a reference to that value is returned.

There are basically four reference types:

classes,

interfaces,

delegates

arrays.

Class type consists of custom user defined data types such as the Class Employee.

Class Employee

Dim empid As Integer

Dim empname As String

Public Sub New()

empid = 10

empname = "Reshmi"

End Sub

End Class

Overloading provides the ability to create multiple methods or properties with the same name, but with different parameters lists.

This is a feature of polymorphism. It is accomplished by using the Overloads keyword in VB.NET.

Class testPublic Overloads Function Add(ByVal x As Integer, ByVal y AsInteger)Return x + yEnd FunctionPublic Overloads Function Add(ByVal x As String, ByVal y AsString)Return x & yEnd FunctionShared Sub main()Dim a As new testDim b As IntegerDim c As Stringb = a.Add(1, 2)c = a.Add("Reshmi", " Nair")System.Console.Writeline(b)System.Console.Writeline(c)End SubEnd Class

In VB.NET by using the Overridablekeyword with the base class method and the Overrideskeyword with the derived class method.

Public Class shapes

Public Overridable Sub display()

Console.WriteLine("Shapes")

End Sub

End Class

Public Class square

Inherits shapes

Public Overrides Sub display()

Console.WriteLine("This is a square")

End Sub

End Class

Public Class rectangle

Inherits shapes

Public Overrides Sub display()

Console.WriteLine("This is a rectangle")

End Sub

End Class

Properties are named members of classes, structs, and interfaces.

They provide a flexible mechanism to read, write, or compute the values of private fields through accessors.

Structures are very similar to classes but there are some restrictions present in the case of structures that are absent in the case of classes.

A structure allows to create own custom data types and it contains one or more members that can be of different data types.

Namespaces are used in .Net to organize class libraries into a hierarchical structure and reduce conflicts between various identifiers in a program.

Namespaces enables reusable components from different companies to be used in the same program without the worry of ambiguity caused by multiple instances of the same identifier.

Namespaces provide a logical organization for programs to exist. Starting with a top level namespace, sub-namespaces are created to further categorize code, based upon its purpose.

The base class library begins at the System namespace.

Nested namespaces within the System namespace are

System.Security

System.IO

System.Data

System.Collection

Boxing is the implicit conversion of a

Value type to a reference type or

To any interface type implemented by this value type.

When boxing occurs, the contents of value type are copied from the stack into the memory allocated on the managed heap.

The new reference type created contains a copy of the value type and can be used by other types that expect an object reference.

UnBoxing is the explicit conversion from

A reference type to a value type or

From an interface type to a value type that implements the interface.

VB.Net does not support the ability to explicitly unbox values.

It relies on the helper functions in the Microsoft.VisualBasic.Helpersnamespace to carry out unboxing.

Enumerations are types that inherit from System.Enum.

The elements of an enumeration are expressed in words rather than numbers, which makes it convenient for understanding the meaning of the value being used.

Enumerations symbolically represent a set of values of one of the primitive integral types.

The type of the elements of an enumeration can be Byte, Short, Integer or Long.

If no type is specified explicitly, the default type is Integer.

Enumeration Type

The runtime supports constructs called delegates, which enable late-bound operations such as method invocation and callback procedures.

With delegates, a program can dynamically call different methods at runtime.

They are type safe, secure, managed objects that always point to a valid object and cannot corrupt the memory of another object.

The closest equivalent of a delegate in other languages is a function pointer, but whereas a function pointer can only reference Shared functions, a delegate can reference both Shared and instance methods.

Delegates are Marshal by Value Objects.

The members of a delegate are the members inherited from class System.Delegate.

A delegate defines the signature and return type of a method. The resulting delegate can reference any method with a matching signature.

Each instance of a delegate can forward a call to one or more methods that take those parameters and return the same type.

Once a method has been assigned to a delegate, it is called when the delegate is invoked.

When ByVal keyword is used, it causes the parameter to be passed by value.

In this case, a copy of the original parameter is passed to the called module.

Thus any changes made to the copy of the parameter do not affect the original value of the parameter.

When ByRef keyword is used, it sends a reference (pointer) to the original value to the called module rather than its copy.

Thus any changes made to the parameter in the function/procedure will cause the original value to be modified.

Ctype is a general cast keyword that coerces an expression into any type.

It returns the result of explicitly converting an expression to a specified data type, object, structure, class, or interface.

If no conversion exists from the type of the expression to the specified type, a compile-time error occurs.

When Ctype is used to perform explicit conversion, execution is faster since it is compiled inline and hence no call to a procedure is involved to perform the conversion.

Integer Type VB.NET CLR Type

8-bit Integer Byte System.Byte

16-bit Integer Short System.Int16

32-bit Integer Integer System.Int32

64-bit Integer Long System.Int64

The .NET Framework provides a run-time environment called the Common Language Runtime, which manages the execution of code and provides services that make the development process easier.

Compilers and tools expose the runtime's functionality and enable you to write code that benefits from this managed execution environment.

Code developed with a language compiler that targets the runtime is called managed code.

dotNET Tutorial for Beginners,India Community Initiative

Microsoft Visual Studio 2010 byMichael Halvorson, Microsoft

Microsoft Visual Basic 6.0 by Francesco Balena ,Microsoft Press

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