Basic data types
| Data type |
CLR type structure |
Size |
Value range |
|
Boolean |
System.Boolean |
2 bytes |
True or False. |
|
Byte |
System.Byte |
1 byte |
0 through 255 (unsigned). |
|
Char |
System.Char |
2 bytes |
0 through 65535 (unsigned). |
|
Date |
System.DateTime |
8 bytes |
0:00:00 on January 1, 0001 through 11:59:59 PM on December 31, 9999. |
|
Decimal |
System.Decimal |
16 bytes |
0 through +/-79,228,162,514,264,337, 593,543,950,335 with no decimal point;
0 through +/-7.922816251426433 7593543950335 with 28 places to the right of the decimal; smallest nonzero number is
+/-0.0000000000000 000000000000001 (+/-1E-28). |
|
Double
(double-precision floating-point) |
System.Double |
8 bytes |
1.797693134862 31570E+308 through
-4.940656458412 46544E-324 for negative values; 4.940656458412 46544E-324 through 1.79769313486231570E+308 for positive values |
|
Integer |
System.Int32 |
4 bytes |
-2,147,483,648 through 2,147,483,647. |
|
Long
(long integer) |
System.Int64 |
8 bytes |
-9,223,372,036,854, 775,808 through 9,223,372,036,854, 775,807. |
|
Object |
System.Object (class) |
4 bytes |
Any type can be stored in a variable of type Object. |
|
Short |
System.Int16 |
2 bytes |
-32,768 through 32,767. |
|
Single
(single-precision floating-point) |
System.Single |
4 bytes |
-3.4028235E+38 through -1.401298E-45 for negative values; 1.401298E-45 through 3.4028235E+38 for positive values. |
|
String
(variable-length) |
System.String (class) |
Depends on implementing platform |
0 to approximately 2 billion Unicode characters. |
|
User-Defined Type
(structure) |
(inherits from System.ValueType) |
Depends on implementing platform |
Each member of the structure has a range determined by its data type and independent of the ranges of the other members. |
example :
Module
Module1
Sub Main()
Dim iCount AsInteger 'declaring an integer variable
Dim cLetter AsChar 'declaring a character variable
Dim strName AsString 'declaring a string variable
iCount = 10
cLetter = "L"
strName = "Easy Steps"
System.Console.WriteLine(iCount) 'printing into the console
System.Console.WriteLine(cLetter)
System.Console.WriteLine(strName)
EndSub
EndModule
User defined data types
Class
A class is a way to bind the data and its associated functions together. It allows the data and functions to be hidden if necessary, from external use. When defining a class we are creating a new abstract data type that can be treated like any other built in type.
syntax :
[Public | Protected | Friend | Protected Friend | Private] Class classname
[Variable, Property, Method and Event Declarations]
End Class
example :
Module
Module1
PublicClass Person 'declaring the class
Dim iAge As Integer
Dim strName As String
PublicSub SetDetails(ByVal age AsInteger, ByVal nameAs String)
iAge = age
strName = name
EndSub
PublicSub GetDetails()
System.Console.WriteLine(iAge)
System.Console.WriteLine(strName)
EndSub
EndClass
Sub Main()
Dim FirstPerson AsNew Person 'creating a class variable (object)
FirstPerson.SetDetails(27, "Erick") 'calling a member function
FirstPerson.GetDetails()
EndSub
EndModule
Structure
A structure associates one or more members with each other and with the structure itself. When you declare a structure, it becomes a composite data type and you can declare variables of that type.
syntax :
[Public | Protected | Friend | Protected Friend | Private] Structure structname
{Dim | Public | Friend | Private} member1 As datatype1
...
{Dim | Public | Friend | Private} memberN As datatypeN
End Structure
example :
Module
Module1
PublicStructure Person 'declaring the structure
Dim iAge AsInteger
Dim strName As String
PublicSub SetDetails(ByVal age AsInteger, ByVal name AsString)
iAge = age
strName = name
EndSub
PublicSub GetDetails()
System.Console.WriteLine(iAge)
System.Console.WriteLine(strName)
EndSub
EndStructure
Sub Main()
Dim FirstPerson As New Person 'creating a structure variable
FirstPerson.SetDetails(27, "Erick") 'calling a memberfunction
FirstPerson.GetDetails()
EndSub
End Module
Program execution control Statements
If...Then...Else Statements
An If...Then...Else statement is the basic conditional statement. If the expression in the If statement is True, the statements enclosed by the If block are executed. If the expression is False, each of the ElseIf expressions is evaluated.
syntax :
If Expression [ Then ] StatementTerminator
[ Block ]
[ ElseIfStatement+ ]
[ Block ]
[ ElseStatement ]
[ Block ]
End If StatementTerminator
example :
Module
Module1
Sub Main()
DimiNumber AsInteger
iNumber = System.Console.ReadLine()
IfiNumber < 5 Then
System.Console.WriteLine("Number is Less than Five")
Else
System.Console.WriteLine("Number is Greater than Five")
EndIf
EndSub
EndModule
Select Case
A Select Case statement executes statements based on the value of an expression.
syntax :
Select [ Case ] Expression StatementTerminator
[ CaseStatement+ ]
....
[ CaseElseStatement ]
End Select StatementTerminator
example :
Module
Module1
Sub Main()
Dim x As Integer = 10
SelectCase x
Case 5
Console.WriteLine("x = 5")
Case 10
Console.WriteLine("x = 10")
Case 20
Console.WriteLine("x = 20 – 10")
Case 30
Console.WriteLine("x = 30")
EndSelect
EndSub
EndModule
While Do While
A While or Do loop statement loops based on a Boolean expression. A While loop statement loops as long as the Boolean expression evaluates to True;
syntax :
1) While Expression StatementTerminator
[ Block ]
End While StatementTerminator
2) Do [ WhileOrUntil Expression ] StatementTerminator [ Block ]
Loop [ WhileOrUntil Expression ] StatementTerminator
example :
Module
Module1
Sub Main()
Dim x As Integer
x = 3
DoWhile x > 0
Console.WriteLine("Do While x > 0")
x -= 1
Loop
x = 3
While x < 5
Console.WriteLine("While x < 5")
x += 1
EndWhile
Do
Console.WriteLine("While x = 2")
x -= 1
LoopWhile x > 2
EndSub
End Module
For Loop
For/Next loops enable you to evaluate a sequence of statements multiple times.
syntax :
For [Expression]
[Block]
Next
example :
Module
Module1
Sub Main()
Dim x As Integer
For x = 1 To 10
System.Console.WriteLine("VB Dot Net in Easy Steps")
Next x
EndSub
End Module
For Each Loop
A For Each...Next statement loops based on the elements in an expression. A For Each statement specifies a loop control variable and an enumerator expression.
syntax :
For Each LoopControlVariable In Expression StatementTerminator
[ Block ]
Next [Expression ] StatementTerminator
example :
Module
Module1
Sub Main()
Dim x(9) As Integer
Dim i As Integer="2"> = 0
For i = 0 To 9
x(i) = i + 1
Next
ForEach y AsInteger In x
System.Console.WriteLine(y)
Next
EndSub
End Module