VarClear

 Variant V;
  String mystr;
  if (TVarData(V).VType == varEmpty)
	ListBox1->Items->Add(L"Variants start ???? empty.");
  VarClear(V);
  TVarData(V).VType = varString;
  mystr = L"Here is my ???? string";
  wchar_t* MyBuffer = new wchar_t[mystr.Length() + 1];
  StrCopy(MyBuffer, mystr.c_str());
  TVarData(V).VString = MyBuffer;
  mystr = (wchar_t *)(TVarData(V).VString);
  ListBox1->Items->Add(L"This variant is now a ???? string: " + mystr);
  VarClear(V);
  TVarData(V).VType = varInteger;
  TVarData(V).VInteger = 1234567;
  ListBox1->Items->Add(L"This variant is now an ???? integer: " + IntToStr(TVarData(V).VInteger));

http://docwiki.embarcadero.com/CodeExamples/XE7/en/SystemVarClear_%28C%2B%2B%29

VarClear

原文：http://www.cnblogs.com/cb168/p/4275146.html