return a NULL iterator?

I have a vector containing a struct of customer_info and a function that searches that vector for a customer name and returns an iterator to that customer. I want to be able to return A Null iterator is no matches are found ( if that is possible ) but I can't get it to work right. Here is what I have

Code:

vector<Customer_Info>::const_iterator Customer_Manager::Find_Customer(string name)
{
    int length = name.size();
    string name2;
    bool match = false;
    int x = 0;
    char selection;
    
    for (int i = 0; i <= (length - 1); i++)
        name[i] = toupper(name[i]);
    
    vector <vector <Customer_Info>::iterator> temp_list;
    vector <vector <Customer_Info>::iterator>::iterator temp_iter;
    vector<Customer_Info>::iterator iter;
    for (iter = customer_list.begin(); iter != customer_list.end(); ++iter)
    {
        name2 = iter->name.substr(0, length);
        if (name == name2)
        {
            temp_list.push_back(iter);
            match = true;
            cout<<x+1 <<")  " <<iter->name <<"   " <<iter->address1 <<endl;
            x++;
        }
    }
    cout<<endl;
    if (x == 0)
        cout<<"No Matching Fields!" <<endl;
    else
        cout<<"Enter Selection";
    cout<<"<0> to Exit ";

    while (true)
    {
        cin>>selection;
        cin.ignore();
        if (selection == '0')
        {
            return iter = NULL;
        }
        if (selection > 0 && selection <= (x + 1) )
            return temp_list.at(x);
        cout<<"Incorrect Selection" <<endl;
    };
}

at the part marked in red I get this error

Code:

155 C:\Dev-Cpp\Dispatch Planner\Customer_Functions.cpp no match for 'operator=' in 'iter = 0' 
 note C:\Dev-Cpp\include\c++\3.4.2\bits\stl_iterator.h:587 candidates are: __gnu_cxx::__normal_iterator<Customer_Info*, std::vector<Customer_Info, std::allocator<Customer_Info> > >& __gnu_cxx::__normal_iterator<Customer_Info*, std::vector<Customer_Info, std::allocator<Customer_Info> > >::operator=(const __gnu_cxx::__normal_iterator<Customer_Info*, std::vector<Customer_Info, std::allocator<Customer_Info> > >&)

Any Ideas as to what is wrong? Or if you can even do it like that?

No, you can't do it that way. An iterator is not a pointer. Try returning customer_list.end() --- the end() method for a standard container actually returns one past the end of the container.

Yup, Thats what I thought. Ok, I'll go about this a whole different way. Thanx