OpenOffice.org BASIC Guide.pdf - OpenOffice.org wiki

Conversion Functions 46
B = A ' Creates error message
In the example shown, the assignment of the test string to a date variable makes no sense,
so the Basic interpreter reports an error. The same applies when attempting to assign a
string to a Boolean variable:
Dim A As String
Dim B As Boolean
A = "test"
B = A ' Creates error message
Again, the basic interpreter reports an error.
These error messages can be avoided by checking the program before an assignment, in
order to establish whether the content of the variable to be assigned matches the type of
the target variable. OpenOffice.org Basic provides the following test functions for this
purpose:
IsNumeric(Value)
checks whether a value is a number.
IsDate(Value)
checks whether a value is a date.
IsArray(Value)
checks whether a value is an array.
These functions are especially useful when querying user input. For example, you can check
whether a user has typed a valid number or date.
If IsNumeric(UserInput) Then
ValidInput = UserInput
Else
ValidInput = 0
MsgBox "Error message."
End If
In the previous example, if the UserInput variable contains a valid numerical value, then
this is assigned to the ValidInput variable. If UserInput does not contain a valid number,
ValidInput is assigned the value 0 and an error message is returned.
While test functions exist for checking numbers, date details and arrays in OpenOffice.org
Basic, a corresponding function for checking Boolean values does not exist. The
functionality can, however, be imitated by using the IsBoolean function:
Function IsBoolean(Value As Variant) As Boolean