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Basic of VBScript Language for QTP

What is VBScript?

  • Based on the Visual Basic family of languages
  • Supports object oriented features
  • Interpreted
  • Loosely Typed
Syntax Rules
  • VBScript is not case sensitive
  • Each statement can only exist on one line
  • Statements can be either simple statements or compound statements
Naming Rules
  • Must begin with a letter or the underscore 
  • Good: count, strInfo, _data
  • Bad: 2day, 4get, *count violate this rule.
  • Cannot contain special characters except the underscore
  • Good: Names using alphabets, numbers and the underscore.
  • Bad: Names using symbols and other special characters.
  • Cannot match a reserved word
  • Bad: for, if, Select
  • Must be unique within a context
  • Must be less than 256 characters
Naming Convention

objDescriptiveName
obj
  Three letter prefix for the data type
DescriptiveName

  • A descriptive name for the variable
  • First letter of each word in upper case
Literal Types

Numeric

  • 1
  • 3.14
  • 3E7

Boolean

  • True
  • False

Characters

  • “Hello World”
  • “123 Straw Lane”
  • “43210”
  • Date

#07/21/2006#

Variables

Dim variableName

  • Variables hold values that can change during program execution
  • They function just like temporary storage locations
Constants:

Const constantName = value

  • Constant names hold values that cannot change during program execution

  • Constants should be used in place of hard-coded values

Operations
  • Operations are the many forms of computations, comparisons etc that can be performed in VB
  • Most operations are binary in the form:
  • operand1 operator operand2
  • Other operations are unary in the form
  • operator operand1
  • When an operator has 2 symbols, you cannot separate them with a space:
  • Good: 2 <> 3
  • Bad: 2 <  > 3
Arithmetic
  • Used to perform calculations
  • Both operands must be numeric values
  • The result is a numeric value
+    Addition
-    Subtraction, Negation
*    Multiplication
/    Division
^    Exponent
Mod    Modulo

Comparison:

  • Used to compare the value of two items
  • Both operands must be of the same data type
  • The result is a Boolean value

=
Equality
<>
Inequality
<
Less than
>
Greater than
<=
Less than or equals
>=
Greater than or equals

Logical

•

  • Used to reduce Boolean values into a single Boolean value
  • Both operands must be Boolean values
  • The result is a Boolean value
And
Conjunction
Or
Disjunction
Not
Negation
•

And Truth Table:

  • Conjunction
  • Used when both conditions are required
Operand1
Operand2
Result
T
T
T
T
F
F
F
T
F
F
F
F

Or Truth Table

  • Disjunction
  • Used when either condition is sufficient
Operand1
Operand2
Result
T
T
T
T
F
T
F
T
T
F
F
F

Not Truth Table

  • Unary Operand
  • Used to change the value of a condition
Operand 1
Result
T
F
F
T
Assignment

  • Changes the value of a variable
  • =
  • Uses the same symbol as an equality check operator.
  • Assignment only occurs when used in any of the following forms:
  • variable = literal value
  • variable = expression
  • variable = variable
Concatenation:

  • Combines 2 data types for display as a string
  • &
Branching
  • Allows you to avoid running certain sections of your code
  • Code is only executed when a condition (or conditions) evaluate to True
  • Provides a single application the ability to react differently to different input values
If
If condition Then
    statement(s)
End If

  • Performs an operation only if the condition evaluates to True

  • Used when an action is either performed or not performed.

If…Else

If condition Then
    statement(s)
Else
    statement(s)
End If

  • Performs the If portion only if the condition evaluates to True and the Else portion otherwise.
  • Used in an either or scenario when an operation is always performed.
If…ElseIf

If condition1 Then
    statement(s)
ElseIf condition2 Then
    statement(s)
Else
    statement(s)
End If

  • Only one section can be executed even if many conditions evaluate to True.
  • Used in a multiple choice scenario
  • Inclusion of the last Else is optional
Loops
  • Allows you to repeat running certain sections of your code
  • Code executes when a condition (or conditions) evaluate to True
  • Be careful with Loops. They can result in infinite processing.
  • Forms
      • Entry Condition
  • Entry only when a initial condition is met
  • Iterated
  • Repeats for a specific number of times
Loop Questions:

1.
Can this loop ever be entered
    If no, then you don’t need the loop
Can this loop ever be exited
   If no, then you have an infinite loop

While
 While condition
    statement(s)
Wend

  • Entry Condition Loop
  • Simplest form of the loop
  • Requires manual modification of the loop condition
For
For variable = start To finish [Step change]
    statement(s)
Next

  • Iterated Loop
  • Favored because all the loop details are in the definition statement

Examples:

Declaring Variables:

dim name
name=some value

Assigning Values to Variables

name="Hege"
i=200 

If....Then.....Else

if i=10 Then
   msgbox "Hello"
   i = i+1
end If


if i=10 then
   msgbox "Hello"
else
   msgbox "Goodbye"
end If 

if payment="Cash" then
   msgbox "You are going to pay cash!"
 elseif payment="Visa" then
   msgbox "You are going to pay with visa."
 elseif payment="AmEx" then
   msgbox "You are going to pay with American Express."
 else
   msgbox "Unknown method of payment."
end If    


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