RAD Studio VCL Reference
Variants.VarCheckEmpty Function

Raises an exception if a specified variant's value is Unassigned.

procedure VarCheckEmpty(const V: Variant);
VarCheckEmpty(const Variant V);

Call VarCheckEmpty when your code requires that a System::Variant have a value, and you want to raise an exception if it doesn't. VarCheckEmpty checks whether the System::Variant specified by V has a value of Unassigned. If so, it raises an EVariantTypeMismatchError exception. 

To check whether the System::Variant is Unassigned without raising an exception, use the VarIsEmpty function instead. To check whether the System::Variant's value is undefined, use the VarIsClear function instead.

Note: Do not confuse an Unassigned variant with a System::Variant whose value is Null. A Null variant is still assigned, but has the value Null. Unlike unassigned variants, Null variants can be used in expressions and can be converted to other types of variants.


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