__w64

I am trying to port an application from 32-bit to 64-bit windows environment. There are a lot of warnings like these when i compile my code on 64-bit :-

mbtext.cxx(2249) : warning C4244: 'argument' : conversion from '__w64 int' to 'int', possible loss of data
mbtext.cxx(2354) : warning C4244: 'argument' : conversion from '__w64 int' to 'int', possible loss of data

This warning is at lot of places.
"__w64" : Not much help is available to know more about this type.

Please suggest appropriate resolution for this warning.

Thanks,
- Navin

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__w64

George Cai
__w64 is not a type! __w64 says that in a 64bit envioronment this variable sized type (variable sized depeneding on the compiler), and on a 32bit compiler its 32bit. So assigning this types from one to another fires the warning!

Example: DWORD_PTR is a DWORD that is allowed to carry a pointer, so it is 64bit wide on a 64bit system. Assigning it to a DWORD (32bit) value fires the above warning!
Rubal Jain
This warning is a result of /Wp64. See docs on /Wp64.

This is a portability warning. It is telling you that the code you're writing may not be portable to a 64-bit architecture.

The resolution is to either eliminate the explicit or implicit cast that would shorten a 64-bit type to a 32-bit type. Or, if you will never compile this code to a 64-bit machine, disable /Wp64 (Detect 64-bit Portability Errors under the C/C++ settings).

Note to Daniel Rieck: this thread really belongs in the Visual C++ language forum. This is not a .NET Framework question.
__w64

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__w64

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George Cai

Rubal Jain