Beware of intptr

signed integer type capable of holding a pointer to void

2025-11-16

Written by: xiaobin

The default version uses MSVC >=1930, which is Visual Studio 2022.

• Why use intptr_t?
  On some platforms pointer types have much larger size than any integral type. I believe an example of such as platform would be IBM AS/400 with virtual instruction set defining all pointers as 128-bit. A more recent example of such platform would be Elbrus. It uses 128-bit pointers which are HW descriptors rather than normal addresses.

How do I use it?

• intptr_t

I find intptr_t rather less useful, except possibly as a way station when casting, 
to avoid the dread warning about changing signedness and integer size in the same cast. 
(Writing portable code that passes -Wall -Werror on all relevant architectures can be a bit of a struggle.)

• INT_PTR

Also, intptr_t is the C99/C++11 standard alternative, but INT_PTR predates them.

INT_PTR

• .cpp

MFC App Wizard

Generate dialog-based

	INT_PTR nResponse = dlg.DoModal();
	if (nResponse == IDOK)
	{
		// TODO: Place code here to handle when the dialog is
		//  dismissed with OK
	}
	else if (nResponse == IDCANCEL)
	{
		// TODO: Place code here to handle when the dialog is
		//  dismissed with Cancel
	}
	else if (nResponse == -1)
	{
		TRACE(traceAppMsg, 0, "Warning: dialog creation failed, so application is terminating unexpectedly.\n");
		TRACE(traceAppMsg, 0, "Warning: if you are using MFC controls on the dialog, you cannot #define _AFX_NO_MFC_CONTROLS_IN_DIALOGS.\n");
	}

Recommend

• This is closely related to the operating system!

It’s not recommended to use definitions from the operating system when you don’t need them!

Ref

• MSVC Version
• intptr_t(optional)