Article ID: 168440
If you try to pass an __int64 variable to the ostream operator <<, you get the following error:
error C2593: 'operator <<' is ambiguous
There is no operator << for __int64 type defined for the ostream class.
Define your own version of operator <<. The following sample code section shows a simple solution for << operator that converts the __int64 variable to a char * type and passes it to the ostream << operator.
Microsoft has confirmed that this is a bug in the Microsoft products that are listed in the "Applies to" section.
This problem was corrected in Microsoft Visual C++ .NET.
The following sample program demonstrates the problem and workaround: