Qt-interest Archive, May 2007
link problem of 'static QPtrList<QListViewItem> p_listviewitem '
Message 1 in thread
hi again today
i define a static member in my code
class LVIPtr
{
public :
static QPtrList<QListViewItem> p_listviewitem;
static void setupListviewPoint();
//...........
};
void LVIPtr::setupListviewPoint()
{
do something like p_listviewitem.append ;
}
and in another class
class myApps
{
public:
void getPtr();
}
void myApps::getPtr()
{
QPtrList<QListViewItem> ptr=LVIPtr::p_listviewitem;
//..........
}
gcc said:
apps.o: In function
`QPtrList<QListViewItem>::operator=(QPtrList<QListViewItem> const&)':
/usr/lib/qt/include/qptrlist.h:72: undefined reference to
`LVIPtr::p_listviewitem'
lviptr.o: In function `QPtrList<QListViewItem>::append(QListViewItem const*)':
/usr/lib/qt/include/qptrlist.h:82: undefined reference to
`LVIPtr::p_listviewitem'
/usr/lib/qt/include/qptrlist.h:82: undefined reference to
`LVIPtr::p_listviewitem'
lviptr.o: In function `QPtrList<QListViewItem>::first()':
/usr/lib/qt/include/qptrlist.h:109: undefined reference to
`LVIPtr::p_listviewitem'
lviptr.o: In function `QPtrList<QListViewItem>::next()':
/usr/lib/qt/include/qptrlist.h:111: undefined reference to
`LVIPtr::p_listviewitem'
collect2: ld returned 1 exit status
make: *** [apps] Error 1
what's the problem?
then i tried to define it:
QPtrList<QListViewItem> LVIPtr::p_listviewitem;
in main
gcc said:
main.cc: In function 'int main(int, char**)':
main.cc:26: error: invalid use of qualified-name 'LVIPtr::p_listviewitem'
make: *** [main.o] Error 1
how to do this?
regards
--
[ signature omitted ]
Message 2 in thread
On 07.05.07 00:29:44, jiang jefix wrote:
> i define a static member in my code
> class LVIPtr
> {
> public :
> static QPtrList<QListViewItem> p_listviewitem;
> static void setupListviewPoint();
> //...........
> };
> void LVIPtr::setupListviewPoint()
> {
> do something like p_listviewitem.append ;
> }
>
> and in another class
> class myApps
> {
> public:
> void getPtr();
> }
> void myApps::getPtr()
> {
> QPtrList<QListViewItem> ptr=LVIPtr::p_listviewitem;
> //..........
> }
>
> gcc said:
> apps.o: In function
> `QPtrList<QListViewItem>::operator=(QPtrList<QListViewItem> const&)':
> /usr/lib/qt/include/qptrlist.h:72: undefined reference to
> `LVIPtr::p_listviewitem'
This means that you don't link against the library in which LVIPtr is,
so just add that library via the .pro file that builds apps.o like this:
LIBS += path-to-lib/libname.a
If its a static lib. If you build a shared lib you'd need something like
LIBS += -lname -Lpath-to-lib
Andreas
--
[ signature omitted ]
Message 3 in thread
maybe i dont say clear
note that LVIPtr is a class i defined in my apps
it has a static member:
static QPtrList<QListViewItem> p_listviewitem;
and in another class myApps:
i want to get p_listviewitem which is a static member defined in class LVIPtr
class myApps
{
void getPtr();
//........
};
void myApps::getPtr()
{
QPtrList<QListViewItem> *ptr=LVIPtr::p_listviewitem; // this is
line 189 in //apps.cc
//............
}
and gcc said:
apps.o: In function `myApps::getPtr()':
/home/jefix/study/qt/myapps/apps.cc:189: undefined reference to
`LVIPtr::p_listviewitem'
collect2: ld returned 1 exit status
make: *** [apps] Error 1
what's the problem?
thanks
2007/5/7, Andreas Pakulat <apaku@xxxxxx>:
> On 07.05.07 00:29:44, jiang jefix wrote:
> > i define a static member in my code
> > class LVIPtr
> > {
> > public :
> > static QPtrList<QListViewItem> p_listviewitem;
> > static void setupListviewPoint();
> > //...........
> > };
> > void LVIPtr::setupListviewPoint()
> > {
> > do something like p_listviewitem.append ;
> > }
> >
> > and in another class
> > class myApps
> > {
> > public:
> > void getPtr();
> > }
> > void myApps::getPtr()
> > {
> > QPtrList<QListViewItem> ptr=LVIPtr::p_listviewitem;
> > //..........
> > }
> >
> > gcc said:
> > apps.o: In function
> > `QPtrList<QListViewItem>::operator=(QPtrList<QListViewItem> const&)':
> > /usr/lib/qt/include/qptrlist.h:72: undefined reference to
> > `LVIPtr::p_listviewitem'
>
> This means that you don't link against the library in which LVIPtr is,
> so just add that library via the .pro file that builds apps.o like this:
>
> LIBS += path-to-lib/libname.a
>
> If its a static lib. If you build a shared lib you'd need something like
>
> LIBS += -lname -Lpath-to-lib
>
> Andreas
>
> --
> Good news. Ten weeks from Friday will be a pretty good day.
>
> --
> To unsubscribe - send a mail to qt-interest-request@xxxxxxxxxxxxx with "unsubscribe" in the subject or the body.
> List archive and information: http://lists.trolltech.com/qt-interest/
>
>
--
[ signature omitted ]
Message 4 in thread
This is a C++ error.
Static class member variables have to be instantiated/initialized outside of the
class declaration. Example:
// declare the class in file foo.hxx
class foo_t
{
public:
static int bar_;
};
// initialize foo_t::bar_ in file foo.cxx
int foo_t::bar_ = 0;
Hope this helps,
Paul.
jiang jefix wrote:
> maybe i dont say clear
> note that LVIPtr is a class i defined in my apps
> it has a static member:
> static QPtrList<QListViewItem> p_listviewitem;
>
> and in another class myApps:
> i want to get p_listviewitem which is a static member defined in class
> LVIPtr
> class myApps
> {
> void getPtr();
> //........
> };
>
> void myApps::getPtr()
> {
> QPtrList<QListViewItem> *ptr=LVIPtr::p_listviewitem; // this is
> line 189 in //apps.cc
> //............
> }
>
> and gcc said:
> apps.o: In function `myApps::getPtr()':
> /home/jefix/study/qt/myapps/apps.cc:189: undefined reference to
> `LVIPtr::p_listviewitem'
> collect2: ld returned 1 exit status
> make: *** [apps] Error 1
>
> what's the problem?
> thanks
>
> 2007/5/7, Andreas Pakulat <apaku@xxxxxx>:
>> On 07.05.07 00:29:44, jiang jefix wrote:
>> > i define a static member in my code
>> > class LVIPtr
>> > {
>> > public :
>> > static QPtrList<QListViewItem> p_listviewitem;
>> > static void setupListviewPoint();
>> > //...........
>> > };
>> > void LVIPtr::setupListviewPoint()
>> > {
>> > do something like p_listviewitem.append ;
>> > }
>> >
>> > and in another class
>> > class myApps
>> > {
>> > public:
>> > void getPtr();
>> > }
>> > void myApps::getPtr()
>> > {
>> > QPtrList<QListViewItem> ptr=LVIPtr::p_listviewitem;
>> > //..........
>> > }
>> >
>> > gcc said:
>> > apps.o: In function
>> > `QPtrList<QListViewItem>::operator=(QPtrList<QListViewItem> const&)':
>> > /usr/lib/qt/include/qptrlist.h:72: undefined reference to
>> > `LVIPtr::p_listviewitem'
>>
>> This means that you don't link against the library in which LVIPtr is,
>> so just add that library via the .pro file that builds apps.o like this:
>>
>> LIBS += path-to-lib/libname.a
>>
>> If its a static lib. If you build a shared lib you'd need something like
>>
>> LIBS += -lname -Lpath-to-lib
>>
>> Andreas
>>
>> --
>> Good news. Ten weeks from Friday will be a pretty good day.
>>
>> --
>> To unsubscribe - send a mail to qt-interest-request@xxxxxxxxxxxxx with
>> "unsubscribe" in the subject or the body.
>> List archive and information: http://lists.trolltech.com/qt-interest/
>>
>>
>
> --
> To unsubscribe - send a mail to qt-interest-request@xxxxxxxxxxxxx with
> "unsubscribe" in the subject or the body.
> List archive and information: http://lists.trolltech.com/qt-interest/
>
--
[ signature omitted ]
Message 5 in thread
I've attached a better example. Try compiling it with and without the
int foo_t::bar_ = 0;
line.
Paul.
Paul Koshevoy wrote:
> This is a C++ error.
>
> Static class member variables have to be instantiated/initialized outside of the
> class declaration. Example:
>
> // declare the class in file foo.hxx
> class foo_t
> {
> public:
> static int bar_;
> };
>
> // initialize foo_t::bar_ in file foo.cxx
> int foo_t::bar_ = 0;
>
> Hope this helps,
> Paul.
>
>
> jiang jefix wrote:
>> maybe i dont say clear
>> note that LVIPtr is a class i defined in my apps
>> it has a static member:
>> static QPtrList<QListViewItem> p_listviewitem;
>>
>> and in another class myApps:
>> i want to get p_listviewitem which is a static member defined in class
>> LVIPtr
>> class myApps
>> {
>> void getPtr();
>> //........
>> };
>>
>> void myApps::getPtr()
>> {
>> QPtrList<QListViewItem> *ptr=LVIPtr::p_listviewitem; // this is
>> line 189 in //apps.cc
>> //............
>> }
>>
>> and gcc said:
>> apps.o: In function `myApps::getPtr()':
>> /home/jefix/study/qt/myapps/apps.cc:189: undefined reference to
>> `LVIPtr::p_listviewitem'
>> collect2: ld returned 1 exit status
>> make: *** [apps] Error 1
>>
>> what's the problem?
>> thanks
>>
>> 2007/5/7, Andreas Pakulat <apaku@xxxxxx>:
>>> On 07.05.07 00:29:44, jiang jefix wrote:
>>>> i define a static member in my code
>>>> class LVIPtr
>>>> {
>>>> public :
>>>> static QPtrList<QListViewItem> p_listviewitem;
>>>> static void setupListviewPoint();
>>>> //...........
>>>> };
>>>> void LVIPtr::setupListviewPoint()
>>>> {
>>>> do something like p_listviewitem.append ;
>>>> }
>>>>
>>>> and in another class
>>>> class myApps
>>>> {
>>>> public:
>>>> void getPtr();
>>>> }
>>>> void myApps::getPtr()
>>>> {
>>>> QPtrList<QListViewItem> ptr=LVIPtr::p_listviewitem;
>>>> //..........
>>>> }
>>>>
>>>> gcc said:
>>>> apps.o: In function
>>>> `QPtrList<QListViewItem>::operator=(QPtrList<QListViewItem> const&)':
>>>> /usr/lib/qt/include/qptrlist.h:72: undefined reference to
>>>> `LVIPtr::p_listviewitem'
>>> This means that you don't link against the library in which LVIPtr is,
>>> so just add that library via the .pro file that builds apps.o like this:
>>>
>>> LIBS += path-to-lib/libname.a
>>>
>>> If its a static lib. If you build a shared lib you'd need something like
>>>
>>> LIBS += -lname -Lpath-to-lib
>>>
>>> Andreas
>>>
>>> --
>>> Good news. Ten weeks from Friday will be a pretty good day.
>>>
>>> --
>>> To unsubscribe - send a mail to qt-interest-request@xxxxxxxxxxxxx with
>>> "unsubscribe" in the subject or the body.
>>> List archive and information: http://lists.trolltech.com/qt-interest/
>>>
>>>
>> --
>> To unsubscribe - send a mail to qt-interest-request@xxxxxxxxxxxxx with
>> "unsubscribe" in the subject or the body.
>> List archive and information: http://lists.trolltech.com/qt-interest/
>>
>
> --
> To unsubscribe - send a mail to qt-interest-request@xxxxxxxxxxxxx with "unsubscribe" in the subject or the body.
> List archive and information: http://lists.trolltech.com/qt-interest/
>
#include <iostream>
#include <iostream>
using std::cout;
using std::endl;
class foo_t
{
public:
static int bar_;
};
// int foo_t::bar_ = 0;
int main()
{
cout << foo_t::bar_ << endl;
return 0;
}
