VBS control structures for if do whilw.docx
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VBScript is a lightweight scripting language used for web development and automation, supporting various data types including variant, integer, long, single, double, string, boolean, date, nothing, empty, and null. The document outlines VBScript operators for arithmetic, comparison, logical operations, type conversion, assignment, and bitwise operations, as well as control statements for flow control including conditional statements and loops. It also discusses error handling methods and the use of the select case statement for managing multiple conditions.
VBS control structures for if do whilw.docx
- 1. VBSCRIPT DATATYPES VBScript (Visual Basic Scripting Edition) is a lightweight scripting language used primarily for web development and automation tasks. It supports several data types for handling different types of data Variant: Default type, can store any kind of data. Integer: Whole numbers (from -32,768 to 32,767). Long: Larger integers (from -2,147,483,648 to 2,147,483,647). Single: Single-precision floating-point numbers. Double: Double-precision floating-point numbers. String: Text or character data. Boolean: Logical values (True or False). Date: Date and time values. Nothing: Object variable with no reference. Empty: Uninitialized variable Variant Description: In VBScript, all variables are of type Variant by default. A Variant can hold any type of data (e.g., string, integer, date). Dim myVar myVar = "Hello, World!" ' String MsgBox myVar ' Outputs "Hello, World!" myVar = 100 ' Integer MsgBox myVar ' Outputs 100
- 2. myVar = #12/25/2024# ' Date MsgBox myVar ' Outputs "12/25/2024" Integer Stores whole numbers between -32,768 and 32,767 Dim num num = 1500 MsgBox num ' Outputs 1500 Long Used for storing larger integers, ranging from -2,147,483,648 to 2,147,483,647. Dim largeNum largeNum = 1234567890 MsgBox largeNum ' Outputs 1234567890 Single Stores single-precision floating-point numbers (decimal values). Dim floatNum floatNum = 3.14159
- 3. MsgBox floatNum ' Outputs 3.14159 Double Used to store double-precision floating-point numbers for higher precision. Dim doubleNum doubleNum = 1234567890.987654321 MsgBox doubleNum ' Outputs 1234567890.987654 String Stores a sequence of characters, including text or numbers as text. Dim str str = "Hello, VBScript!" MsgBox str ' Outputs "Hello, VBScript!" Boolean Stores logical values: True or False. Dim isTrue isTrue = True MsgBox isTrue ' Outputs -1 (VBScript treats True as -1) Dim isFalse isFalse = False MsgBox isFalse ' Outputs 0
- 4. Date Used to store date and time values. Dim currentDate currentDate = Now ' Get current date and time MsgBox currentDate ' Outputs current date and time Dim specificDate specificDate = #12/25/2024# MsgBox specificDate ' Outputs "12/25/2024" Nothing Represents a variable that has no object reference or value. It is not a data type per se, but used for object variables. Dim obj Set obj = Nothing ' Releases object reference MsgBox IsObject(obj) ' Outputs False Empty Represents an uninitialized variable. It is used to check if a variable has been assigned a value or not. Dim emptyVar MsgBox IsEmpty(emptyVar) ' Outputs True NULL: Represents the absence of a value (usually used with database or object-related operations).
- 5. Dim myNullVar myNullVar = Null MsgBox IsNull(myNullVar) ' Outputs True VBScript Operators: Dim a, b, result a = 10 b = 3 result = a + b MsgBox result result = a - b MsgBox result result = a * b MsgBox result result = a / b MsgBox result
- 6. result = a b MsgBox result result = a Mod b MsgBox result Comparison Operators Dim a, b a = 10 b = 5 If a = b Then MsgBox "Equal" Else MsgBox "Not Equal" End If If a > b Then MsgBox "a is greater than b" End If Logical Operators
- 7. Dim a, b a = True b = False If a And b Then MsgBox "Both are True" Else MsgBox "At least one is False" End If If Not a Then MsgBox "a is False" Else MsgBox "a is True" End If Concatenation Dim firstName, lastName, fullName firstName = "John" lastName = "Doe" fullName = firstName & " " & lastName
- 8. MsgBox fullName Type Conversion Operators These operators are used to convert one data type to another. Operator Description Example CInt Converts to Integer CInt(expression) CDbl Converts to Double CDbl(expression) CStr Converts to String CStr(expression) CDate Converts to Date CDate(expression) CLng Converts to Long CLng(expression) Dim num, strNum num = 3.14 strNum = CStr(num) ' Converts to string MsgBox strNum Dim dateStr, dateVal dateStr = "12/25/2024" dateVal = CDate(dateStr) ' Converts to date MsgBox dateVal Assignment Operators
- 9. These operators are used to assign values to variables. Operator Description Example = Assignment a = b += Add and assign a += b (a = a + b) -= Subtract and assign a -= b (a = a - b) *= Multiply and assign a *= b (a = a * b) /= Divide and assign a /= b (a = a / b) &= Concatenate and assign a &= b (a = a & b) Dim a, b a = 5 b = 3 a += b ' a = a + b, so a becomes 8 MsgBox a Bitwise Operators These operators are used for bit-level operations. Operator Description Example And Bitwise AND a And b Or Bitwise OR a Or b
- 10. Operator Description Example Xor Bitwise XOR a Xor b Not Bitwise NOT Not a Shl Bitwise Shift Left a Shl b Shr Bitwise Shift Right a Shr b Dim a, b, result a = 5 ' 0101 in binary b = 3 ' 0011 in binary result = a And b MsgBox result result = a Or b MsgBox result VBScript Control Statements
- 11. control statements are used to control the flow of execution in a program. These statements allow for conditional branching, looping, and error handling. If...Then...Else: Used for conditional branching. For...Next: Used for iterating a specific number of times. For Each...Next: Used to iterate through a collection or array. Do...Loop: Used for creating loops with conditions checked before or after execution. Exit statements: Used to exit loops or procedures prematurely. Select Case: Used for multiple condition checks. Error Handling: On Error Resume Next and On Error GoTo 0 for managing runtime errors. 1. Conditional Statements If...Then Statement The If...Then statement evaluates a condition and executes code if the condition is true. If condition Then ' Code to execute if condition is True End If Example: Dim num num = 10
- 12. If num > 5 Then MsgBox "The number is greater than 5" End If If...Then...Else Statement The If...Then...Else statement adds an Else part to the If statement, allowing alternative code to run when the condition is false. SYNTAX: If condition Then ' Code to execute if condition is True Else ' Code to execute if condition is False End If Example: Dim num num = 3 If num > 5 Then MsgBox "The number is greater than 5" Else MsgBox "The number is 5 or less" End If c. If...Then...ElseIf...Else Statement
- 13. This allows multiple conditions to be evaluated. SYNTAX: If condition1 Then ' Code to execute if condition1 is True ElseIf condition2 Then ' Code to execute if condition2 is True Else ' Code to execute if all conditions are False End If Example: Dim num num = 7 If num > 10 Then MsgBox "The number is greater than 10" ElseIf num > 5 Then MsgBox "The number is greater than 5 but less than or equal to 10" Else MsgBox "The number is 5 or less" End If 2. Looping Statements
- 14. a. For...Next Loop The For...Next loop is used for iterating a specific number of times. SYNTAX: For counter = start To end ' Code to execute on each iteration Next Example: Dim i For i = 1 To 5 MsgBox "Iteration number: " & i Next b. For Each...Next Loop This loop is used to iterate over a collection or array. Syntax: For Each item In collection ' Code to execute for each item Next Example:
- 15. Dim colors colors = Array("Red", "Green", "Blue") For Each color In colors MsgBox "Color: " & color Next c. Do...Loop Statement The Do...Loop provides a flexible way to create loops. You can loop while a condition is true or until a condition is true. SYNTAX: Do While...Loop (loop until the condition is false): Do While condition ' Code to execute while condition is True Loop Example: Dim num num = 1 Do While num <= 5 MsgBox "Current number: " & num num = num + 1
- 16. Loop Do Until...Loop (loop until the condition is true): SYNTAX: Do Until condition ' Code to execute until condition is True Loop Example: Dim num num = 1 Do Until num > 5 MsgBox "Current number: " & num num = num + 1 Loop Do...Loop While (check condition after the loop executes): SYNTAX: Do ' Code to execute Loop While condition
- 17. Example: Dim num num = 1 Do MsgBox "Current number: " & num num = num + 1 Loop While num <= 5 Do...Loop Until (check condition after the loop executes): SYNATX: Do ' Code to execute Loop Until condition Example: Dim num num = 1 Do MsgBox "Current number: " & num num = num + 1 Loop Until num > 5
- 18. 3. Exit Statements a. Exit For This statement is used to exit a For...Next loop prematurely. Syntax: For counter = 1 To 10 If counter = 5 Then Exit For End If ' More code here Next Example: Dim i For i = 1 To 10 If i = 5 Then Exit For ' Exit the loop when i is 5 End If MsgBox "Iteration number: " & i Next b. Exit Do
- 19. This statement is used to exit a Do...Loop prematurely. Synatx: Do While condition If someCondition Then Exit Do End If ' More code here Loop Example: Dim num num = 1 Do If num = 3 Then Exit Do ' Exit the loop when num is 3 End If MsgBox "Current number: " & num num = num + 1 Loop c. Exit Sub This exits a Sub procedure.
- 20. Syntax: Sub MySub() If someCondition Then Exit Sub End If ' More code here End Sub Example: Sub MySub() Dim num num = 10 If num > 5 Then MsgBox "Exiting Sub" Exit Sub ' Exit the Sub End If MsgBox "This line will not execute" End Sub ' Call the Sub MySub() d. Exit Function
- 21. This exits a Function procedure. Syntax: Function MyFunction() If someCondition Then Exit Function End If ' More code here End Function Example: Function MyFunction() Dim result result = 10 If result > 5 Then MyFunction = result ' Assign the result and exit the function Exit Function End If MyFunction = result ' This line won't be reached if result > 5 End Function MsgBox MyFunction()
- 22. 4. Error Handling a. On Error Resume Next This statement tells VBScript to continue execution with the next statement if an error occurs. Syntax: On Error Resume Next ' Code that might cause an error If Err.Number <> 0 Then ' Handle the error End If Example: On Error Resume Next Dim x x = 1 / 0 ' This will cause an error (division by zero) If Err.Number <> 0 Then MsgBox "An error occurred: " & Err.Description End If 5. Select Case Statement The Select Case statement allows for multiple conditions to be checked. It is an alternative to using multiple If...Then statements.
- 23. Syntax: Select Case expression Case value1 ' Code to execute if expression equals value1 Case value2 ' Code to execute if expression equals value2 Case Else ' Code to execute if no case matches End Select Example: Dim num num = 3 Select Case num Case 1 MsgBox "The number is 1" Case 2 MsgBox "The number is 2" Case 3 MsgBox "The number is 3" Case Else
- 24. MsgBox "The number is not 1, 2, or 3" End Select