RAD Studio VCL Reference
Variants.VarIsClear Function

Indicates whether the specified variant has an undefined value.

function VarIsClear(const V: Variant): Boolean;
Boolean VarIsClear(const Variant V);

VarIsClear returns true if the given variant's value is undefined. The value can be undefined for any of several reasons: 

The System::Variant may have had its value set to Unassigned

The System::Variant's value may be an interface type that has been set to nil (Delphi) or NULL (C++). 

The System::Variant may be a custom variant that returns true from its IsClear method. 

In all other cases, the function result is false.

Note: Do not confuse an unassigned variant with a Null variant. 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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