Introduction to XML
CPAN 660
Lecture #2: Syntax and Structure
files are identified by the extension .aspx. The following elements can be used with :
• Directives:
• Code Blocks: …
The code inside the script tag must be declaration, which means it must be placed either in a function or a subroutine, so we can execute this code later.
• Server Controls: or
• Data binding expressions:
• Render code (inline): and
• Server Side Comments:
Storing Information in using VB syntax:
Variables are labeled memory location for storing information. as well as the other .NET languages is strongly typed. This means any variable used in the code must be declared with a specific data type. The keyword Dim is used in to declare a variable. supports 12 different types, which are: Integer, Byte, Short, Long, Single, Double, Decimal, String , Char, Date, Boolean and Object. For example:
Dim strName As String
Dim intMark As Integer
Variables can be initialized using the assignment operator, For example
strName=”John Smith”
intMark=75
You can also declare and initialize the variable in one statement as shown in the following example:
Dim strName As String =”John Smith”
Dim intMark As Integer=75
Arithmetic Operators:
|Operation |Operator |
|Addition |+ |
|Subtraction |- |
|Multiplication |* |
|Division |/ |
|Exponentiation |^ |
|Negation |- |
|Modulus |MOD |
Note:
Strings can be concatenated using &. For example:
Dim strFName As String =”John”
Dim strLName As String = “ Smith”
Dim strFullName
strFullName=strFName & “ , “ & strLName
Arrays
Arrays are used to store a sequence of items of the same data type. For example, the following statement declares an array of size 6:
Dim intMarks(5) As Integer
Then each element must be initialized using the assignment operator:
intMarks(0)= 60
intMarks(1)= 78
intMarks(2)= 70
intMarks(3)= 86
intMarks(4)= 96
intMarks(5)= 69
Each element in the array is accessed via a zero based integer value called index. For the above example, the first item in the array is accessed by the index of zero:
also supports multi-dimensional arrays. The following example shows how to create a two dimensional array of 3 rows and 3 columns:
Dim strArray(2,2) As Integer
strArray(0,0)=”value1”
strArray(0,1)=”value2”
strArray(0,2)=”value3”
strArray(1,0)=”value4”
strArray(1,1)=”value5”
strArray(1,2)=”value6”
strArray(2,0)=”value7”
strArray(2,1)=”value8”
strArray(2,2)=”value9”
Constants
A Constant is a labelled memory location to store constant data. The keyword Const is used in to declare a constant. For example:
Const TAX=0.015
Relational (Comparison) Operators
|Operation |Operator |
|Equality |= |
|Inequality | |
|Less than |< |
|Less than or equal to | |
|Greater than or equal to |>= |
Logical Operators
• NOT
• AND
• OR
Decision making:
• If … Then Structure: For example:
If intCount =10 Then
‘ do something
End If
• If … Then … Else Structure: For example:
If intCount =10 Then
‘ do something
Else
‘ do something else
End If
• If .. Then .. ElseIf Structure: For example
If intCount =1 Then
‘ take action 1
ElseIf intCount=2 Then
‘ take action 2
Else
‘ take other action
End If
• Select Case Structure: For example:
Select Case answer
Case “yes”
‘Take action 1
Case “no”
‘ Take action 2
Case Else
‘ Take optional default action
End Select
Iteration :
• For .. Next Structure
Used when the number of iterations is known in advance. For example
For intCount= 0 To 10
‘ do something
Next intCount
• Do While Structure
Used to loop unknown number of times, as long as the specified condition is true. For example:
Dim intCount As Integer = 0
Do While intCount ................
................
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