c++.windows.32-bits - Previous definition different errror
- chris elliott (37/37) Jun 17 2003 I have a header file for my wxhatch application, which contains a collec...
- Walter (6/13) Jun 17 2003 collection
- chris elliott (5/22) Jun 17 2003 That worked fine,
- Wichetael (18/45) Jun 17 2003 It's more of a 'feature' of other compilers. In essence by *defining* th...
- Walter (3/6) Jun 17 2003 Yes, that would be better.
- chris elliott (7/13) Jun 17 2003 yes, I would live with it if it said the definitons were the same....
- Walter (4/6) Jun 17 2003 The way DM works is the way the language is defined to work. You might b...
I have a header file for my wxhatch application, which contains a collection
of lines like this
const wxString space = wxT(' ');
which are used in several code .cpp files.
On linking the files I get errors
Error 1: Previous Definition Different : ?space 3VwxString B (const
wxString space)
My compile and link lines are
dmc -c -o -mn -W -H -D__NT__ -DWIN32 -D__WIN32__ -D__WIN95__ -D__WINDOWS__ -
D__W
XMSW__ -D__SC__ -D__WXDEBUG__ -I..\..\wxWindows\include -I..\..\wxWindows\l
ib\_
sc -I..\..\wxWindows\contrib\include -I..\..\wxWindows/src/regex;..\..\wxWin
dows
/src/png;..\..\wxWindows/src/jpeg;..\..\wxWindows/src/zlib;..\..\wxWindows/s
rc/t
iff wxhatch.cpp -owxhatch.obj
.... more lines all the same
link /DELEXECUTABLE /RC -L/exet:nt/su:windows wxhatch.obj wxhcombo.obj
bitmenu.
obj mcanvas.obj mytext.obj tchild.obj trchild.obj lchild.obj mchild.obj
raddlg.o
bj textdlg.obj startdlg.obj srdlg.obj mnudlg.obj cfgdlg.obj tooldlg.obj
mcdlg.ob
j , wxhatch.exe, wxhatch, ..\..\wxWindows\lib\ wx_sc.lib
..\..\wxWindows\lib\stc
_sc.lib png_sc tiff_sc jpeg_sc zlib_sc shell32_sc wsock32_sc advapi32
comctl32 c
omdlg32 ctl3d32 gc gdi32 kernel32 ole32 oleaut32 snn user32 uuid
OPTLINK (R) for Win32 Release 7.50B1
Copyright (C) Digital Mars 1989 - 2001 All Rights Reserved
bitmenu.obj(bitmenu) Offset 000B1H Record Type 0091
Error 1: Previous Definition Different : ?wxH_VersionString 3VwxString B
(con
st wxString wxH_VersionString)
thanks
chris
Jun 17 2003
"chris elliott" <biol75 york.ac.uk> wrote in message news:bcmojg$q29$1 digitaldaemon.com...I have a header file for my wxhatch application, which contains acollectionof lines like this const wxString space = wxT(' '); which are used in several code .cpp files. On linking the files I get errors Error 1: Previous Definition Different : ?space 3VwxString B (const wxString space)Move the line in the header to a .cpp file. Replace the line in the header with: extern const wxString space;
Jun 17 2003
"Walter" <walter digitalmars.com> wrote in message news:bcnd45$1cs2$1 digitaldaemon.com..."chris elliott" <biol75 york.ac.uk> wrote in message news:bcmojg$q29$1 digitaldaemon.com...That worked fine, So is this a bug in DM or a "feature" of the other compilers? chrisI have a header file for my wxhatch application, which contains acollectionof lines like this const wxString space = wxT(' '); which are used in several code .cpp files. On linking the files I get errors Error 1: Previous Definition Different : ?space 3VwxString B (const wxString space)Move the line in the header to a .cpp file. Replace the line in the header with: extern const wxString space;
Jun 17 2003
It's more of a 'feature' of other compilers. In essence by *defining* the constant in the header file you *define* it multiple times as the header is included in multiple objects, (as in files, not in OO instances.) Strictly speaking this is not allowed by the standard, (at least afaik,) and what you should do instead, (as Walter suggested,) is *declare* the constant in the header file, but *define* it in a source file so that it is included in only one object. Some compilers simply silently ignore multiple definitions and drop all the definitions that come after the first one. But that is of course a non-standard approach and it is ill advised to rely on this if you want your code to be portable. btw, Walter, why does the compiler report that the previous definition is different? Shouldn't it report that it is a multiple definition since the definitions are actually the same? Hope I got all my terms ans stuff right ;) Regards, Remko van der Vossen. "chris elliott" <chris ampleforth.u-net.com> wrote in message news:bcnl2i$1kl8$1 digitaldaemon.com..."Walter" <walter digitalmars.com> wrote in message news:bcnd45$1cs2$1 digitaldaemon.com...header"chris elliott" <biol75 york.ac.uk> wrote in message news:bcmojg$q29$1 digitaldaemon.com...I have a header file for my wxhatch application, which contains acollectionof lines like this const wxString space = wxT(' '); which are used in several code .cpp files. On linking the files I get errors Error 1: Previous Definition Different : ?space 3VwxString B (const wxString space)Move the line in the header to a .cpp file. Replace the line in thewith: extern const wxString space;That worked fine, So is this a bug in DM or a "feature" of the other compilers? chris
Jun 17 2003
"Wichetael" <wichetael gmx.net> wrote in message news:bcnn06$1mat$1 digitaldaemon.com...btw, Walter, why does the compiler report that the previous definition is different? Shouldn't it report that it is a multiple definition since the definitions are actually the same?Yes, that would be better.
Jun 17 2003
"chris elliott" <chris ampleforth.u-net.com> yes, I would live with it if it said the definitons were the same.... Different definitons made me think it was a linker bug chris "Walter" <walter digitalmars.com> wrote in message news:bcnpjg$1p52$2 digitaldaemon.com..."Wichetael" <wichetael gmx.net> wrote in message news:bcnn06$1mat$1 digitaldaemon.com...isbtw, Walter, why does the compiler report that the previous definitionthedifferent? Shouldn't it report that it is a multiple definition sincedefinitions are actually the same?Yes, that would be better.
Jun 17 2003
"chris elliott" <chris ampleforth.u-net.com> wrote in message news:bcnl2i$1kl8$1 digitaldaemon.com...That worked fine, So is this a bug in DM or a "feature" of the other compilers?The way DM works is the way the language is defined to work. You might be seeing an extension done by other compilers.
Jun 17 2003