'LONG' to 'WNDPROC'

[David19]

i'm getting a warning when i try to subclass the listview control like:

WNDPROC OrigList = (WNDPROC) SetWindowLongPtr (hwndList, GWL_WNDPROC,
(__int3264)(LONG_PTR) ListProc) ;

SetWindowLongPtr returns a LONG and i need it to cast to WNDPROC.

warning C4312: conversion from 'LONG' to 'WNDPROC' of greater size

[Ajay Vijay]

SetWindowLongPtr returns LONG_PTR and not LONG. There is no need to double typecast it.

[David19]

Oh right, i confused it with SetWindowLong( ). double typecast ListProc?

[Ajay Vijay]

By double-typecasting, I meant this (not casting to 'double'):(__int3264)(LONG_PTR) ListProc

[David19]

thats what i really mean :)

[David19]

if i don't double typecast ListProc, i get an another warning.

[Ajay Vijay]

What warning?
'(LONG_PTR) ListProc' should suffice. What is the type of 'ListProc' ?

[David19]

warning C4244: 'argument' : conversion from 'LONG_PTR' to 'LONG', possible loss of data

ListProc is defined as:

LRESULT CALLBACK ListProc (HWND hwnd, UINT message,
WPARAM wParam, LPARAM lParam);

[Ajay Vijay]

I see the weird complication in the function and the LONG_PTR. The symbol SetWindowLongPtr, eventually maps to SetWindowLong API, and takes LONG only. But LONG_PTR is type-defined with something else.

But you can still use only one typecasting to __int3264.