compiler-warning-level-1-c4621.md

description	title	ms.date	f1_keywords	helpviewer_keywords	ms.assetid
Learn more about: Compiler Warning (level 1) C4621	Compiler Warning (level 1) C4621	11/04/2016	C4621	C4621	40931bd9-cb89-497e-86f0-cec9f016c63c

Compiler Warning (level 1) C4621

no postfix form of 'operator --' found for type 'type', using prefix form

There was no postfix decrement operator defined for the given type. The compiler used the overloaded prefix operator.

This warning can be avoided by defining a postfix -- operator. Create a two-argument version of the -- operator as shown below:

// C4621.cpp
// compile with: /W1
class A
{
public:
   A(int nData) : m_nData(nData)
   {
   }

   A operator--()
   {
      m_nData -= 1;
      return *this;
   }

   // A operator--(int)
   // {
   //    A tmp = *this;
   //    m_nData -= 1;
   //    return tmp;
   // }

private:
   int m_nData;
};

int main()
{
   A a(10);
   --a;
   a--;   // C4621
}