Arrays
An array is a contiguous area in the memory referred to by a common name. It is a series of variables having the same data type. Arrays are used to store related data values. VBScript allows you to store a group of common values together in the same location. These values can be accessed with their reference numbers.
An array is made up of two parts, the array name and the array subscript. The subscript indicates the highest index value for the elements within the array. Each element of an array has a unique identifying index number by which it can be referenced. VBScript creates zero based arrays where the first element of the array has an index value of zero.
Declaring Arrays
An array must be declared before it can be used. Depending upon the accessibility, arrays are of two types:
• Local Arrays
A local array is available only within the function or procedure, where it is declared.
• Global Arrays
A global array is an array that can be used by all functions and procedures. It is declared at the beginning of the VBScript Code.
The Dim statement is used to declare arrays. The syntax for declaring an array is as follows:
Dim ArrayName(subscriptvalue)
Where, ArrayName is the unique name for the array and SubscriptValue is a numeric value that indicates the number of elements in the array dimension within the array.
Example:
Dim No_Passengers(3)
The No_Passengers can store 4 values.
Assigning values to the array
No_Passengers(0) = 1
No_Passengers(1) = 2
No_Passengers(2) = 3
No_Passengers(3) = 4
Static and Dynamic Arrays:
VBScript provides flexibility for declaring arrays as static or dynamic.
A static array has a specific number of elements. The size of a static array cannot be altered at run time.
A dynamic array can be resized at any time. Dynamic arrays are useful when size of the array cannot be determined. The array size can be changed at run time.
Next we will deal with user defined procedures, functions and subroutines.
This post is third in the VB Script and QTP series.
Here we shall talk about user defined procedures.
Procedures are set of executable statements.
In VBScript, there are two types of procedures:
Sub Procedures
Function Procedures
Sub Procedures
A sub procedure is a series of VBScript statements, enclosed by Sub and End Sub statements which perform actions but do not return a value. A sub procedure can take arguments. If a sub procedure doesn’t receive any arguments, its Sub statement must include an empty parenthesis().
The following Sub procedure uses two intrinsic, or built-in, VBScript functions, MsgBox and InputBox , to prompt a user for information. It then displays the results of a calculation based on that information. The calculation is performed in a Function procedure created using VBScript. The Function procedure is shown after the following discussion.
Sub ConvertTemp()
temp = InputBox("Please enter the temperature in degrees F.", 1)
MsgBox "The temperature is " & Celsius(temp) & " degrees C."
End Sub
Function Procedures
A function procedure is a series of VBScript statements enclosed by the Function and End Function statements. A function procedure is similar to a sub procedure but it can return value to the calling function. A function procedure can take arguments (constants, variables or expressions that are passed to it by a calling procedure). If a function procedure has no arguments, it Function statement must include an empty set of parenthesis. A function returns a value by assigning a value to its name in one or more statements of the procedure. Since VBScript has only one base data type, a function always returns a variant.
In the following example, the Celsius function calculates degrees Celsius from degrees Fahrenheit. When the function is called from the ConvertTemp Sub procedure, a variable containing the argument value is passed to the function. The result of the calculation is returned to the calling procedure and displayed in a message box.
Sub ConvertTemp()
temp = InputBox("Please enter the temperature in degrees F.", 1)
MsgBox "The temperature is " & Celsius(temp) & " degrees C."
End Sub
Function Celsius(fDegrees)
Celsius = (fDegrees - 32) * 5 / 9
End Function
Tips:
To get data out of a procedure, you must use a Function. Remember, a Function procedure can return a value; a Sub procedure can't.
AFunction in your code must always be used on the right side of a variable assignment or in an expression.
To call a Sub procedure from another procedure, type the name of the procedure along with values for any required arguments, each separated by a comma. The Call statement is not required, but if you do use it, you must enclose any arguments in parentheses.
The following example shows two calls to the MyProc procedure. One uses the Call statement in the code; the other doesn't. Both do exactly the same thing.
Call MyProc(firstarg, secondarg)
MyProc firstarg, secondarg
Notice that the parentheses are omitted in the call when the Call statement isn't used.
