VBScript Reference Manual for InduSoft Web Studio

VBScript Reference Manual InduSoft Web Studio
Variable Data Types and Subtypes
All variables in VBScript are a data type called Variant. This means that you do not (and cannot)
explicitly declare the variable type. In fact, with VBScript you do not need the Dim statement to allocate
storage for a variable. At runtime, the Parser in the VBScript Scripting Engine determines the Variant
data subtype to be used. These correspond to the more traditional classifications of data types (see
chart below).
Variant data subtypes
Subtype Description
Boolean Either True or False
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
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.
The Parsers choice of data subtype will depend on how the variable is used in a statement or function.
Note that a variable’s subtype can change within a code segment.
Data Subtype Identification
If it is important to determine the Variant data subtype used at runtime, you may use any of the three
categories of functions to determine the data subtype:
• The VarType(variable) function which returns a code based on the Variant data subtype used
• Various IsXxxx(variable) functions which return boolean values indicating whether the variable
is of a specific data subtype.
• A TypeName(variable) function which returns a string based indicating the data subtype
Example: If varType(a) = vbInteger Then
Msgbox “a is an Integer”
EndIf
Data Subtype Conversion
VBScript provides several functions that convert a variable from one data subtype to another. Since
VBScript uses the Variant data type, these functions are not generally required. However, when
passing data between IWS (or CEView) and VBScript, or calling built-in IWS functions from VBScript
where variables need to be put into the proper argument format, these VBScript data subtype
conversion functions can be very useful.
Example: a = 4.2
b = cInt (a) ‘ b is an Integer with a value of 4
12 InduSoft, Ltd.