Assignment and Kind

[gelarimer]

iret below is defind as a 4 byte integer, and Loword(), a win32 macro, returns a 2 byte integer. Should the assignement be stated as,

iret = Loword(wParam)

or,

iret = Int4(Loword(wParam))

Thank you for a reply.

[Steven_L_Intel1]

Either one is ok. Fortran defines implicit conversion between numeric types and kinds. But you'll get sign-extension which you may not want. Consuder using zext instead of int4.

[gelarimer]

Thank you.

Also, I noticedin the documentation for INT (Chap. 9 Intrinsic Procedures) that the table with Specific names is missing the names for the 1st twoitems. Can you tell me what these Specific names are?

[Steven_L_Intel1]

There aren't specific names for those. Specific names are a relic of Fortran 66 and should generally be avoided.

Use generics, with the optional KIND= specifier if needed. For example:

INT (X,1)

[Jugoslav_Dujic]

You have to be very careful with LOWORD/HIWORD. I'm not sure what's the exact prototype of VF-supplied ones, but I tend to use the following statement functions instead, as I've been badly beaten with it:

INTEGER XLOWORD, XHIWORD, SLOWORD, SHIWORD

XLOWORD(i) = IAND(i, Z'FFFF') !Unsigned versions

XHIWORD(i) = ISHL(i, -16)

SLOWORD(i) = INT(INT(IAND(i, Z'FFFF'),2)) !Signed versions

SHIWORD(i) = INT(INT(ISHL(i, -16),2))

The usage depends on the context, and what the API documentation says that the result should be casted into -- WORD means "unsigned", short means "unsigned".
The difference comes to light when the e.g. bit 15 of the loword/hiword is set. (E.g. Hex 0000FFFF - The "unsigned" versions will return 65535, and signed -1).

For example, mouse messages (WM_MOUSEMOVE) can contain negative coordinates when the mouse is captured; in this case, signed versions are called for. If you, OTOH, use the signed version for WM_COMMAND, your control IDs greater than 32767 will not work.

I (hope I) have the complete and correct list of usages per window message (that's the most common place where *LOWORD is used).

[gelarimer]

Thanks Steve, Jugoslav. Info was very helpful. Jugoslav, thanks for the detailed info on using LOWORD/HIWORD: something I had not thought about before now.