Compiler Warning (level 2) C4826
Visual Studio 2005
Error Message
Conversion from 'type1 ' to 'type_2' is sign-extended. This may cause unexpected runtime behavior.This warning indicates that the compiler performed sign extension when a 32-bit pointer was cast to a 64-bit variable.
If the extension was performed on a windows HANDLE type, it is safe to ignore this warning. If the extension was performed on a pointer type, you should modify the cast to prevent the sign extension (see example below). You can also prevent or permit the sign extension by declaring the pointer with the __sptr, __uptr modifier.
C4826 is off by default. See Compiler Warnings That Are Off by Default for more information.
Example
The following sample generates C4826.
// C4826.cpp
// compile with: /W2 /c
#include <windows.h>
#pragma warning(default: 4826)
void * __ptr64 F1 (void * __ptr32 P ) {
return (void * __ptr64)P; // C4826
// try the following line instead
// return (void * __ptr64)(ULONGLONG)(ULONG)P;
}
void * __ptr64 F2 ( void * P ) {
return (void * __ptr64)P; // C4826
// try the following line instead
// return (void * __ptr64)(ULONGLONG)(ULONG)P;
}
unsigned __int64 F3r ( void * P ) {
return (unsigned __int64)P; // C4826
// try the following line instead
// return (unsigned __int64)(ULONGLONG)(ULONG)P;
}
