conversions in 64 bit mode

utcode

in visual studio c++ / x64: what are way safest to convert from: 1.INT_PTR to int? 2.LRESULT to BOOL? 3.LRESULT to int?

CPallini

There is no 'safe way' to do those 'conversions'. On x64 the int data type is a 32-bit integer, while both INT_PTR and LRESULT are 64-bit integers (long long, see Windows Data Types (BaseTsd.h) - Win32 apps | Microsoft Learn[^]), hence such conversions would 'narrow'. Also, I believe there is no 'safe way' to convert a LRESULT to a BOOL, because the former value depends on context (see, for instance, Writing the Window Procedure - Win32 apps | Microsoft Learn[^]).

"In testa che avete, Signor di Ceprano?" -- Rigoletto

Lost User

Hi, If you want to detect overflows, underflows, truncation. The Shell team provided the [intsafe.h header](https://learn.microsoft.com/en-us/windows/win32/api/intsafe/).

wizQ wrote:

1.INT_PTR to int?

The [IntPtrToInt function](https://learn.microsoft.com/en-us/windows/win32/api/intsafe/nf-intsafe-intptrtoint) will at least warn you if the pointer was truncated. CPallini gave great advice, there really isn't a "safe" conversion. But you can at least detect overflows and underflows.

utcode

can one change int to LRESULT?. change from int c = ... to LRESULT c = ... also change from void func(int p,.. to void func(LRESULT p,... :java:

Lost User

The question is, why would you want to do such a thing? The LRESULT type has a specific meaning and purpose, which is not the same as an int, or any other basic, type.