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Compiler Warning (level 1) C4965
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Compiler Warning (level 1) C4965

Error Message

implicit box of integer 0; use nullptr or explicit cast

Visual C++ 2005 features implicit boxing of value types. An instruction that resulted in a null assignment using Managed Extensions for C++ now becomes an assignment to a boxed int.

For more information, see Implicit Boxing.


The following sample generates C4965.

// C4965.cpp
// compile with: /clr /W1
int main() {
   System::Object ^o = 0;   // C4965

   // the previous line is the same as the following line
   // using Managed Extensions for C++
   // System::Object *o = __box(0);

   // OK
   System::Object ^o2 = nullptr;
   System::Object ^o3 = safe_cast<System::Object^>(0);

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