VBScript Reference Manual for InduSoft Web Studio

VBScript Reference Manual InduSoft Web Studio
VBScript Variables
Variable Data Types and Subtypes
VB and VBA are compiled languages that require you to explicitly declare the variables you are going to
use and their data type. To explicitly declare a VB or VBA variable, you would use the Dim keyword.
The following example shows how VB or VBA would declare the variable x as an integer:
Dim x As Integer
Dim a, b, c As Integer
With VBScript, you also use the Dim statement to explicitly declare a variable. However, you are not
required to explicitly declare variables in VBScript. If you do not explicitly declare a variable, it is
implicitly declared when the variable is used. However, typing (spelling) errors can typically go
undetected until a problem occurs, and then must be detected and corrected. By adding the Option
Explicit command at the beginning of the script, you can force the VBScript Scripting Engine to only
use the variables that are explicitly declared.
Example Dim a, b ‘ explicitly declares the variables a & b
a = 4 ‘ assigns the value of 4 to variable a
b = 4 ‘ assigns the value of 4 to variable b
c = a + b ‘ VBScript will create a variable c, and then perform the
add
Example Option Explicit ‘ Force explicit definition of variables
Dim a, b ‘ declare variables a and b
a = 4 ‘ define variable a
b = 4 ‘ define variable b
c = a + b ‘ will generate an error since c not explicitly declared
Interestingly, VBScript does not allow you declare the variable data type (i.e. integer, real, etc.) in the
Dim statement. In fact, VBScript does not support data Type declarations. This is a major difference
between VBScript and VB/VBA. Instead, all VBScript variables are of a data type called Variant,
meaning the data type can be whatever is required. However, there are a variety of VBScript Variant
data subtypes that correspond to traditional data types familiar to programmers. These variant data
subtypes are:
Variant data subtypes
Subtype Description
Array An indexed list of variants
Boolean Boolean value of either True or False. False has a value of 0, and True has a value of -1.
Byte Contains integer in the range 0 to 255
Currency Floating-point number in the range -922,337,203,685,477.5808 to 922,337,203,685,477.5807
Date(Time) Contains a number that represents a date between January 1, 100 to December 31, 9999
Double Contains a double-precision, floating-point number in the range -1.79769313486232E308 to -
4.94065645841247E-324 for negative values; 4.94065645841247E-324 to
1.79769313486232E308 for positive values
Empty Uninitialized Variant
Error Contains an error number used with runtime errors
Integer Contains integer in the range -32,768 to 32,767
Long Contains integer in the range -2,147,483,648 to 2,147,483,647
Null A variant containing no valid data
Object Contains an object reference. Note that this is not the object itself.
Single Contains a single-precision, floating-point number in the range -3.402823E38 to -1.401298E-45
for negative values; 1.401298E-45 to 3.402823E38 for positive values
String Contains a variable-length string that can be up to approximately 2 billion characters in length.
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