VBScript Reference Manual for InduSoft Web Studio

VBScript Reference Manual InduSoft Web Studio
Data Subtype Identification
The Parser that is part of the VBScript Scripting Engine automatically defines a variable’s data subtype
for you at runtime. However, there are times when the programmer may need to know the variable’s
data subtype. To determine the specific data subtype used, VBScript you can 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
Variant Data Subtype Identification Functions
Variant
Function
Description
IsArray()
IsDate()
IsEmpty()
IsNull()
IsNumeric()
Returns a Boolean value indicating whether a variable is an array
Returns a Boolean value indicating whether an expression can be converted to a date
Returns a Boolean value indicating whether a variable has been initialized.
Returns a Boolean value that indicates whether an expression contains no valid data (Null).
Returns a Boolean value indicating whether an expression can be evaluated as a number
IsObject() Returns a Boolean value indicating whether an expression refers to a valid Automation
object.
TypeName() Returns a string that provides Variant subtype information about a variable
VarType() Returns a value indicating the subtype of a variable
VarType() Function
This function is similar to TypeName except that a numeric value, or ID, is returned that is used to
identify the data subtype. This ID can then, as an example, be used in a flow control statement.
VarType Constants (returned from the VarType() function)
Constant Value Description
vbEmpty 0 Empty (uninitialized)
vbNull 1 Null (no valid data)
vbInteger 2 Integer
vbLong 3 Long Integer
vbSingle 4 Single-precision floating-point number
vbDouble 5 Double-precision floating-point number
vbCurrency 6 Currency
vbDate 7 Date
vbString 8 String
vbObject 9 Object
vbError 10 Error
vbBoolean 11 Boolean
vbVariant 12 Variant (Used only with Arrays)
vbDataObject 13 Data-access Object
vbDecimal 14 Decimal
vbByte 17 Byte
vbArray 8192 Array
Example:
Myval = 23.3
If VarType(Myval) = vbSingle Then
Msgbox “MyVal is a Single Precision Floating Point Number”
End If
76 InduSoft, Ltd.