stl list & iterators

[kfaday]

I've got a list for XML objects. i'm using the std::list

i declare an iteraror, and set it to the beginning of the list

XML::iterator i = this->begin();

then i want to go to the 'num' positon of the list, so i use this for bucle:

for(int ii=0; ii<num ;i++, ii++);

that code is ok, i can see what's on the list.
The problem is that i don't know how to delete that position. the following code doesn't seem to work...

this->erase(i,i);

do you have any ideas? this is my first project with stl.. i've read Eckels Thinking In C++ vol 2 and i can't find anything.. he speaks about a remove method, but i can't use it

thanks!!

[Assmaster]

Erase only takes one iterator parameter. It's simply .erase(i).

But... What's with the usage of the this pointer here? You aren't by any chance deriving from std::list or something? In that case.. Don't.

And what is XML? Hopefully just a typedefed specialization of std::list?

edit: typos..

[Philip Nicoletti]

You can use std::advance() algorithm to move an
iterator from its current position. see code ...

#include <list>
#include <iostream>
#include <algorithm>
#include <iterator>

using namespace std;

int main()
{
    list<int> my_list;

    for (int i=0; i<10; ++i)
        my_list.push_back(i);

    list<int>::iterator it = my_list.begin();

    int num = 5;

    if (num < (int)my_list.size())
        advance(it,num);

    my_list.erase(it);

    copy(my_list.begin(),my_list.end(),ostream_iterator<int>(cout,"\n"));

    return 0;
}

[kfaday]

yes, i am deriving from std::list

class XML;
typedef std::list<XML*> listaXML;
class XML:private listaXML
{
...
void erase(XML::iterator from, XML::iterator to);
}

i'm working on someone's code.. this is something i have to do for university, so i HAVE to use that code. Erase has been overloaded, it doesn't accept 1 parameter:

 void XML::erase(XML::iterator from, XML::iterator to)
  {
    listaXML::iterator i = from;
    for(;i != to; i++)
      delete *i;
    this->listaXML::erase(from,to);
  }

that's why i called

this->erase(i,i);

[Philip Nicoletti]

std::list does have a two argument erase, does your
overload erase() work the same way ? Remember,
when you give a range ot iterators, the "end" iterator
points to one PAST the last element you want to erase.
So the folowing doesn't really make sense :

this->erase(i,i);

If your overloaded erase works the same as normal
STL functions work (and it should to prevent confusion),
you would need to do something like this :

list<int>::iterator it2 = my_list.begin();

advance(it2,5);

list<int>::iterator it1 = it2;
++it2;

my_list.erase(it1,it2);

[kfaday]

that did it!!
problem solved