__w64
Visual Studio .NET 2003
Microsoft Specific
type __w64 identifier
where:
- type
- One of the three types that might cause problems in code being ported from a 32-bit to a 64-bit compiler: int, long, or a pointer.
- identifier
- The identifier for the variable you are creating.
Remarks
The __w64 keyword lets you mark variables, such that when you compile with /Wp64 the compiler will report any warnings that would be reported if you were compiling with a 64-bit compiler.
Any typedef that has __w64 on it must be 32 bits on x86 and 64 bits on ia64.
The __w64 modifier should be specified on any typedefs that change size between 32 bit and 64 bit platforms. For any such type, __w64 should appear only on the 32-bit definition of the typedef. For example:
#ifdef _WIN64 typedef unsigned __int64 size_t; #else typedef _W64 unsigned int size_t; #endif
__w64 is ignored if the compilation does not use /Wp64.
Example
// __w64.cpp
// compile with: /W3 /Wp64
typedef int Int_32;
#ifdef _WIN64
typedef __int64 Int_Native;
#else
typedef int __w64 Int_Native;
#endif
int main()
{
Int_32 i0 = 5;
Int_Native i1 = 10;
i0 = i1; // C4244 64-bit int assigned to 32-bit int
// char __w64 c; error, cannot use __w64 on char
}
END Microsoft Specific
