BUG: Stream Operator << Cannot Handle __int64 Type

• The Standard C++ Library included with: - Microsoft Visual C++, 32-bit Editions, version 5.0

SYMPTOMS

If you try to pass an __int64 variable to the ostream operator <<, you get the following error:

   "error C2593: 'operator <<' is ambiguous"

CAUSE

There is no operator << for __int64 type defined for the ostream class.

RESOLUTION

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.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. We are researching this bug and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

The following sample program demonstrates the problem and workaround:

   //Sample.cpp
   // Compiler Options : /GX

   //#define WORKAROUND   //Uncomment this line to workaround

   #include<iostream>
   using namespace std;

   #ifdef WORKAROUND
   std::ostream& operator<<(std::ostream& os, __int64 i )
   {
       char buf[20];
       sprintf(buf,"%I64d", i );
       os << buf;
       return os;
   }

   #endif

   int main(){
   __int64  i64;

   cout << i64 ;

   return 0;
   }

Keywords          : CRTIss vcbuglist500 kberrmsg kbbuglist
Version           : 5.0
Platform          : NT WINDOWS
Issue type        : kbbug