Introduction to Visual Basic Script Introduction to Visual Basic Script (VBScript)(VBScript)

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Visual Basic Script (VBScript)

Subset of Microsoft Visual Basic IE contains VBScript scripting engine (interpreter) Similar to JavaScript JavaScript used more for client-side scripting

VBScript de facto language for ASP (Active Server Pages)

Dynamic HTML: Client-Side Dynamic HTML: Client-Side Scripting with VBScriptScripting with VBScript

OutlineIntroductionOperatorsData Types and Control StructuresVBScript FunctionsVBScript Example ProgramsArraysString ManipulationClasses and Objects

OperatorsOperators

VBScript Not case-sensitive Provides arithmetic operators, logical operators, concatenation

operators, comparison operators and relational operators Arithmetic operators Similar to JavaScript arithmetic operators Division operator \ Returns integer result

Exponentiation operator ^ Raises a value to a power

Operators Operators

Comparison operators Only symbols for equality operator (=) and

inequality operator () differ from JavaScript Can also be used to compare strings

Logical operators And (logical AND) Or (logical OR) Not (logical negation) Imp (logical implication) Xor (exclusive OR) Eqv (logical equivalence) Not short-circuit; both conditions always

evaluated

Comparison operatorsComparison operators

Standard algebraic equality operator or relational operator

VBScript comparison operator

Example of VBScript condition

Meaning of VBScript condition

= = d = g disequaltog

s r sisnotequaltor

> > y > x yisgreaterthanx

= c >= z cisgreaterthanorequaltoz

Operators Operators

String concatenation Plus sign, + Ampersand, & Formally called string concatenation

operator If both operands are strings, + and & can be

used interchangeably s3 = s1 & s2 s3 = s1 + s2

If varying data types, use ampersand (&) Error: s1 = hello + 22

Data Types and Control StructuresData Types and Control Structures

VBScript has only one data type: Variant Capable of storing different types of data Variant subtypes

Variable names Cannot be keywords Must begin with a letter Max length: 255 characters Letters, digits (0-9) and underscores

OptionExplicit statement Requires variables to be declared before use

Some VBScript variant subtypesSome VBScript variant subtypes

Subtype Range/Description

Boolean True or False Byte Integer in the range 0 to 255 Currency 922337203685477.5808 to 922337203685477.5807 Date/Time 1 January 100 to 31 December 9999

0:00:00 to 23:59:59. Double 1.79769313486232E308 to 4.94065645841247E324 (negative)

1.79769313486232E308 to 4.94065645841247E324 (positive) Empty Uninitialized. This value is 0 for numeric types (e.g., double), False for

booleans and the empty string (i.e., "") for strings. Integer 32768 to 32767 Long 2147483648 to 2147483647 Object Any object type. Single 3.402823E38 to 1.401298E45 (negative)

3.402823E38 to 1.401298E45 (positive) String 0 to ~2000000000 characters.

Data Types and Control StructuresData Types and Control Structures

VBScript control structures Every control structure begins and ends with one or more

keywords (not curly braces as in JavaScript) VBScript does not use statement terminator JavaScript uses semicolons

Parentheses around conditions optional True: variant subtype Boolean True or considered non-zero False: variant subtype Boolean False or considered 0

Comparing VBScript control structures Comparing VBScript control structures to JavaScript control structuresto JavaScript control structures

Data Types and Control StructuresData Types and Control Structures

JavaScript VBScript

1 if ( s == t ) 2 u = s + t; 3 else if ( s > t ) 4 u = r; 5 else 6 u = n;

1 If s = t Then 2 u = s + t 3 ElseIf s > t Then 4 u = r 5 Else 6 u = n 7 End If

JavaScript VBScript

1 switch ( x ) { 2 case 1: 3 alert("1"); 4 break; 5 case 2: 6 alert("2"); 7 break; 8 default: 9 alert("?"); 10 }

1 Select Case x 2 Case 1 3 Call MsgBox("1") 4 Case 2 5 Call MsgBox("2") 6 Case Else 7 Call MsgBox("?") 8 End Select

Comparing JavaScripts if structure to VBScripts If structure

Comparing JavaScripts switch to VBScripts Select Case

Data Types and Control StructuresData Types and Control Structures

Comparing JavaScripts while to VBScripts Do Until

Comparing JavaScripts do/while to VBScripts Do Loop/Until

Comparing JavaScripts for to VBScripts For

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Introduction to Visual Basic Script (VBScript)ContentDynamic HTML: Client-Side Scripting with VBScriptOperatorsOperatorsComparison operatorsSlide 7Data Types and Control StructuresSome VBScript variant subtypesSlide 10Comparing VBScript control structures to JavaScript control structuresSlide 12Slide 13Slide 14