using STL iterators inside a template function

[maximilianus]

Hello to everyone, I need to create a template function that iterate items of a list and save all items in a file. This is what I wrote:

template <class ItemClass>
int Controller::
saveItemsToFile ( list<ItemClass> &_itemsList, const string &filename )
{
int ni = -1;
ofstream outfile ( filename.c_str(), ios_base::out );
if ( !outfile )
cerr << "saveItemsToFile:: unable to open file" << endl;
else
{
ni++;
list<ItemClass>::iterator _nhit = _itemsList.begin();
list<ItemClass>::iterator _nhend = _itemsList.end();
while ( _nhit != _nhend )
{
outfile << *_nhit;
if ( outfile.fail() )
{
cerr << "saveItemsToFile:: file writing error!" << endl;
break;
}
_nhit++;
ni++;
}
outfile.close();
}
return ni;
}

But when I try to compile it I get an error saying
error: need ‘typename’ before ‘std::list<U>::iterator’ because ‘std::list<U>’ is a dependent scope.
So I can't iterate a list inside my template function or there is another way to do it?
Thank you for your help.

[firedraco]

Did you even read the error message? Oo

need ‘typename’ before ‘std::list<U>::iterator’ because ‘std::list<U>’ is a dependent scope.

Also, don't name your variables with an underscore as the first character, those are reserved.

[b2ee]

I guess the compliler doesn't still know what could be objected for "ItemClass" since it's only a template in the compiling phase, only can be initiated in run-time.

Try:
"
typedef typename list<ItemClass>::iterator MyIt;
"
before declaring _nhit.


b2ee

[maximilianus]

Thank you for your help, I solved by declaring _nhit and _nhend in this way:

typename list<ItemClass>::iterator _nhit = _itemsList.begin();
typename list<ItemClass>::iterator _nhend = _itemsList.end();