iterator problem

[Seisouhen]

Hi everyone,
I am a newbie to C++ programming and am running into iterator problems..here are the snippets and the error:

//First, I have a template class called SimpleList that provides linked list functionality with functions like push, pop etc..The idea is to create stack, queues of diff. types (like char, int etc.)
~~bunch of code in between~


//function to search a list for a particular SimipleList object
217 template <class type> string srch_list(list<SimpleList<type> *>
. &list_name, string srch_name)
. {
. string condition;
. typename list<type>::const_iterator iter;
221 for(iter = list_name.begin(); iter != list_name.end(); iter++)
. {
. if (list_name->retn_name() == srch_name)
. condition = "true";
}
return condition;
227 }

//Near the end of the program, I have made a linked list of pointers to SimpleList of objects eg. there is a linked list with pointers to SimpleList objects(eg. of type int)
list<SimpleList<int> *> listSLi;
~code~

//I am calling the function with the line
string condition2;
312 condition2 = srch_list(listSLi, name_stq); //name_stq is the name of stack
I want to search
//I push SimpliList objects into listSLi later on..

But I get the error

ds_projectfinal.cpp: In function `std::string srch_list(std::list<SimpleList<typ
e>*, std::allocator<SimpleList<type>*> >&, std::string) [with type = int]':
ds_projectfinal.cpp:312: instantiated from here
ds_projectfinal.cpp:221: error: no match for 'operator=' in 'iter = (+list_name)
->std::list<_Tp, _Alloc>::begin [with _Tp = SimpleList<int>*, _Alloc = std::allo
cator<SimpleList<int>*>]()'
/usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/bits/stl_list.h:188: note: candida
tes are: std::_List_const_iterator<int>& std::_List_const_iterator<int>::operato
r=(const std::_List_const_iterator<int>&)
ds_projectfinal.cpp:312: instantiated from here
ds_projectfinal.cpp:221: error: no match for 'operator!=' in 'iter != (+list_nam
e)->std::list<_Tp, _Alloc>::end [with _Tp = SimpleList<int>*, _Alloc = std::allo
cator<SimpleList<int>*>]()'
/usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/bits/stl_list.h:254: note: candida
tes are: bool std::_List_const_iterator<_Tp>::operator!=(const std::_List_const_
iterator<_Tp>&) const [with _Tp = int]

I would be grateful if someone could enlighten me with some C++ light...

[Seisouhen]

I changed the iterator to

template <class type> string srch_list(list <type> &list_name, std::string srch_name)
{
string condition;
typename list<type>::const_iterator iter;
for(iter = (*list_name).begin(); iter != (*list_name).end(); iter++)
{
if ((*list_name)->retn_name() == srch_name)
condition = "true";
}
return condition;
}

//with the function being called as

condition = srch_list(listSLi, name_stq);

so, the previous error is gone but there is something else..something more sinister (joking)... but something I cannot make sense of:
It gives me the following error on compiling--

/cygdrive/c/DOCUME~1/Shrestha/LOCALS~1/Temp/ccfdnGQN.o:ds_projectfinal.cpp:(.tex
t+0x9a8): undefined reference to `std::basic_string<char, std::char_traits<char>
, std::allocator<char> > srch_list<int>(std::list<SimpleList<int>*, std::allocat
or<SimpleList<int>*> >&, std::basic_string<char, std::char_traits<char>, std::al
locator<char> >)'
/cygdrive/c/DOCUME~1/Shrestha/LOCALS~1/Temp/ccfdnGQN.o:ds_projectfinal.cpp:(.tex
t+0xdf5): undefined reference to `std::basic_string<char, std::char_traits<char>
, std::allocator<char> > srch_list<int>(std::list<SimpleList<int>*, std::allocat
or<SimpleList<int>*> >&, std::basic_string<char, std::char_traits<char>, std::al
locator<char> >)'
collect2: ld returned 1 exit status

Does not anyone have an idea what is going on?

[Seisouhen]

I changed the above snippet of code to

template <class type>
string srch_list(std::list <type> &list_name, std::string srch_name)
{
string condition;
typename list<type>::const_iterator iter;
for(iter = list_name.begin(); iter != list_name.end(); iter++)
{
if (iter->retn_name() == srch_name)
condition = "true";
}
return condition;
}

//retn_name is a public function in SimpleList base class that returns the private //data member that stores the name of the SimpleList.

//And now the error is:

ds_projectfinal.cpp: In function `std::string srch_list(std::list<type, std::all
ocator<_CharT> >&, std::string) [with type = SimpleList<int>*]':
ds_projectfinal.cpp:340: instantiated from here
ds_projectfinal.cpp:241: error: request for member `retn_name' in `*(&iter)->std
::_List_const_iterator<_Tp>::operator-> [with _Tp = SimpleList<int>*]()', which
is of non-class type `SimpleList<int>* const'

I am having fun talking to myself, but it would be more enjoyable if someone joined me....

If someone could point me in the right direction, it would be really appreciated.

[Seisouhen]

forgot to mention:
line 340 condition = srch_list(listSLi, name_stq);//which calls the function

~code~

template <class type>
string srch_list(std::list <type> &list_name, std::string srch_name)
{
string condition;
typename list<type>::const_iterator iter;
for(iter = list_name.begin(); iter != list_name.end(); iter++)
{
linen 241 if (iter->retn_name() == srch_name)
condition = "true";
}
return condition;
}

[gpraghuram]

HI,
I went through ur code.
The problem is u ra ecalling the function (iter->retn_name() == srch_name)
I think this cant be be done..
Try to access the value directly and i think ur problem will be solved.

Thanks
Raghuram

[Seisouhen]

Thanx gpraghuram,
Well, the problem was that I was trying to access retn_name in iter but lo and behold iter is a pointer and it doesn't have retn_name. What iter points to has the function so I changed the iter in line 241 to (*iter) -> retn_name and everything is fine. By fine I mean it compiles, it still doesn't do what I want it to.

Anyway, thanx to everyone for helping sp. gpraghuram....