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There are six different functions that will assist you in determining if a
particular variable is one Subtype or another. Below I have listed all of
the SubType checking functions:
IsArray(VariableToCheck)
IsDate(VariableToCheck)
IsEmpty(VariableToCheck)
IsNull(VariableToCheck)
IsNumeric(VariableToCheck)
IsObject(VariableToCheck)
All of the above functions return a boolean value (true or false). Some of
the above are self explanatory, however a few are not as clear. I will go
over the ones that need explaining:
IsEmpty(VariableToCheck)
What makes a variable empty? If the variable has been created, but has not been
assigned a value yet it is considered to be empty. This is different from a value that
is empty ("") or equal to NULL.
IsNull(VariableToCheck)
What makes a variable null? A variable is null only when it equals null. You can
set a variable equal to null.
IsNumeric(VariableToCheck)
This will return true if the variable can be converted to a numeric SubType without
generating an error.
Example:
myVar = "Hello"
If IsNumeric(myVar) Then
Response.Write("Variable is numeric.")
Else
Response.Write("Variable is NOT numeric.")
End If
Result:
Variable is NOT numeric.
Another way to determine the variable SubType is the VarType() function.
Syntax:
VarType(VariableToCheck)
The above function will return a number representing the various subtypes. I have listed them
for you below:
| Subtypes |
Value |
Description |
| vbEmpty |
0 |
Not assigned a value |
| vbNull |
1 |
No matching SubType |
| vbInteger |
2 |
Integer |
| vbLong |
3 |
Long |
| vbSingle |
4 |
Single |
| vbDouble |
5 |
Double |
| vbCurrency |
6 |
Currency |
| vbDate |
7 |
Date |
| vbString |
8 |
String |
| vbObject |
9 |
Object |
| vbError |
10 |
Error |
| vbBoolean |
11 |
Boolean (true or false) |
| vbVariant |
12 |
Variant, array of variants only |
| vbDataObject |
13 |
Data Access |
| vbDecimal |
14 |
Decimal |
| vbByte |
17 |
Byte |
| vbArray |
8192 |
Array |
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