Why i cant dereference an iterator at the end of the list?

[Franconet]

Why this code works

Elenco e1;
e1.add(Persona("a","b"));
e1.add(Persona("c","d"));
e1.add(Persona("e","f"));
e1.add(Persona("e","f"));
e1.remove(2);   //list of 4 elements 

but this not work?

Elenco e1;
e1.add(Persona("a","b"));
e1.add(Persona("c","d"));
e1.add(Persona("e","f"));
e1.remove(2);   //list of 3 elements 

This is remove method

Persona Elenco:: remove(int pos){

	
	list<Persona> ::iterator iter=l.begin();

	for(int i=0 ;i<pos;i++){
		iter++;
	
	}

return *(l.erase(iter));      //erase ritorna un iterator 

}

Thanks in advance

[MikeyBoy]

From the reference material on this very site:

Return value
An iterator pointing to the new location of the element that followed the last element erased by the function call. This is the container end if the operation erased the last element in the sequence.

http://www.cplusplus.com/reference/list/list/erase/

What do you think will happen when you try and dereference the end iterator?

[Franconet]

I had change my code on this way

Persona Elenco:: remove(int pos){

	
	list<Persona> ::iterator iter=l.begin();

	for(int i=0 ;i<pos;i++){
		iter++;
	
	}
	Persona p= *iter;
	l.erase(iter);

return p;      //erase ritorna un iterator 


}

Now it works, thanks MikeyBoy :)

[Peter87]

Instead of using a loop you can use std::advance.

std::advance(iter, pos);

http://en.cppreference.com/w/cpp/iterator/advance

[Franconet]

thanks :)