Value of UINT64_MAX ?

[John E]

I'm compiling some cross-platform code which has a test for UINTPTR_MAX, looking like this:-

      #  if (UINTPTR_MAX == 0xFFFFFFFF)
      #    define LG_SIZEOF_PTR 4
      #  elif (UINTPTR_MAX == 0xFFFFFFFFFFFFFFFF)
      #    define LG_SIZEOF_PTR 8
      #  endif

but for VS2015 Community Edition, stdint.h seems to define UNITPTR_MAX like this:-

    #define UINT64_MAX       0xffffffffffffffffui64

    // some stuff...

    #define UINTPTR_MAX  UINT64_MAX

It looks as if 0xFFFFFFFFFFFFFFFF and 0xffffffffffffffffui64 aren't being detected as the same number. Does that make sense to anyone..?

[2kaud]

Don't know about VS2015, but for VS2017 the value of UINTPTR_MAX assigned depends upon whether _WIN64 is defined or not. If _WIN64 is defined then UINPTR_MAX becomes UINT64_MAX otherwise becomes UINT32_MAX.

What value of LG_SIZEOF_PTR are you getting?

This check works OK on my VS2017. When _WIN64 is defined, LG_SIZEOF_PTR is set to 8 and when _WIN64 is not defined it is set to 4.

Are you using Visual Studio IDE? If so you should be able to see highlighted what parts of the preprocessor statements are true and which are not. Try changing temporarily

# if (UINTPTR_MAX == 0xFFFFFFFF)
#    define LG_SIZEOF_PTR 4
#  elif (UINTPTR_MAX == 0xFFFFFFFFFFFFFFFF)
#    define LG_SIZEOF_PTR 8
#  endif

to

# if (UINT64_MAX == 0xFFFFFFFF)
#    define LG_SIZEOF_PTR 4
#  elif (UINT64_MAX == 0xFFFFFFFFFFFFFFFF)
#    define LG_SIZEOF_PTR 8
#  endif

and see what LG_SIZEOF_PTR now becomes.

[2kaud]

Tried it now with VS2015. VS2015 requires an #include <stdint.h> whereas VS2017 doesn't seem to if #include <Windows.h> is also used. However, with the include VS2015 seems to work as expected.

[2kaud]

This is the test code used with VS2015

#include <stdio.h>
#include <stdint.h>

int main()
{
# if (UINTPTR_MAX == 0xFFFFFFFF)
#    define LG_SIZEOF_PTR 4
#  elif (UINTPTR_MAX == 0xFFFFFFFFFFFFFFFF)
#    define LG_SIZEOF_PTR 8
#else
	#define LG_SIZEOF_PTR 0
#  endif

	int a = LG_SIZEOF_PTR;

	printf("ptr : %i\n",  a);
}

This displays 4 when _WIN64 is not defined and 8 when _WIN64 is defined.

The only change is that I've added the catch all final #else to set LG_SIZEOF_PTR to 0 if neither of the #if conditions are true.

[John E]

Thanks 2kaud - I found another version of stdint.h where this was defined:-

#define UINT64_MAX       0xffffffffffffffffULL

So it looks like the different definitions are getting confused somehow. I'll have to leave it till tomorrow when I'm feeling a bit fresher !

[2kaud]

I realise that the code in post #1 probably isn't yours - and you're just the one who has to get it to work with VS. But why do it like this? - why not just use sizeof(int*). This will give the number of bytes used for a pointer - and no messy comparison tests! This would even work for a 16-bit memory computer!

#define UINT64_MAX       0xffffffffffffffffULL
#define UINT64_MAX       0xffffffffffffffffui64

These should be same - as the first is unsigned long long (which should be unsigned 64 bit) and the second is unsigned integer 64 (which is unsigned 64 bit).

[John E]

The global property sheet (Microsoft.Cpp.x64.user.props) is referencing a #include folder belonging to mingw (so I'm picking up the wrong version of stdint.h)

I need to edit my global properties to either remove that folder - or make sure it gets searched after the MSVC ones. Unfortunately, for the life of me I can't remember where to edit my global properties! I can bring up property sheets for an indiviual project - but I've totally forgotten how to edit the global properties...

[2kaud]

Does this help. Its for VS2010, but it seems to be OK for VS2015.

https://social.msdn.microsoft.com/Fo...orum=vcgeneral

[John E]

Hi 2kaud - I followed those instructions and managed to bring up the page for editing Microsoft.Cpp.x64.user.props (i.e. the global properties). It contains a VC++ Directories tab which lists $(VC_IncludePath). There's also the usual C++->General->Additional Include Directories. The problem here is that my additional #include directories are getting searched before the ones in VC++ Directories (whereas I need them to searched after).

Here's the arrangement from VS2005 and you can see that it just had one window for everything. I could re-arrange the search order just by re-ordering the folders there. I guess I could try adding $(VC_IncludePath) to that 2nd window and see if that works...

[2kaud]

What's the content of the PATH environment variable and INCLUDE from a VS command prompt?

[John E]

INCLUDE looks like this:-

INCLUDE=C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\INCLUDE;C:\Progra
m Files (x86)\Microsoft Visual Studio 14.0\VC\ATLMFC\INCLUDE;C:\Program Files (x
86)\Windows Kits\10\include\10.0.10240.0\ucrt;C:\Program Files (x86)\Windows Kit
s\NETFXSDK\4.6.1\include\um;C:\Program Files (x86)\Windows Kits\8.1\include\\sha
red;C:\Program Files (x86)\Windows Kits\8.1\include\\um;C:\Program Files (x86)\W
indows Kits\8.1\include\\winrt;

and PATH looks like this:-

Path=C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\CommonExten
sions\Microsoft\TestWindow;C:\Program Files (x86)\MSBuild\14.0\bin;C:\Program Fi
les (x86)\Microsoft Visual Studio 14.0\Common7\IDE\;C:\Program Files (x86)\Micro
soft Visual Studio 14.0\VC\BIN;C:\Program Files (x86)\Microsoft Visual Studio 14
.0\Common7\Tools;C:\Windows\Microsoft.NET\Framework\v4.0.30319;C:\Program Files
(x86)\Microsoft Visual Studio 14.0\VC\VCPackages;C:\Program Files (x86)\HTML Hel
p Workshop;C:\Program Files (x86)\Microsoft Visual Studio 14.0\Team Tools\Perfor
mance Tools;C:\Program Files (x86)\Windows Kits\8.1\bin\x86;C:\Program Files (x8
6)\Microsoft SDKs\Windows\v10.0A\bin\NETFX 4.6.1 Tools\;C:\Program Files (x86)\N
VIDIA Corporation\PhysX\Common;C:\Program Files\Common Files\Microsoft Shared\Wi
ndows Live;C:\Program Files (x86)\Common Files\Microsoft Shared\Windows Live;C:\
Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\Windows
PowerShell\v1.0\;C:\Program Files (x86)\Windows Live\Shared;C:\Windows\system32\
config\systemprofile\.dnx\bin;C:\Program Files\Microsoft DNX\Dnvm\;C:\Program Fi
les\Microsoft SQL Server\130\Tools\Binn\;C:\Program Files (x86)\Windows Kits\8.1
\Windows Performance Toolkit\;C:\strawberry\c\bin;C:\strawberry\perl\site\bin;C:
\strawberry\perl\bin;C:\Python37;C:\Python37\scripts;C:\Program Files\Meson\;C:\
Program Files (x86)\CMake\bin;C:\Program Files\TortoiseSVN\bin

The good news is that adding $(VC_IncludePath) does seem to be working (see my previous post).

[2kaud]

The good news is that adding $(VC_IncludePath) does seem to be working (see my previous post).

Great!