C++ list::sort <unresolved overloaded function type>

Question

I'm having trouble with c++, trying to sort a playlist with my own functions but it is not working.. I checked many posts speaking about a possible similar problem but I couldn't find any solution. ( c++ - <unresolved overloaded function type> -- I'm having the same error as in this post but not sure to understand what to do then).

May I have a hint please? :) Here is my function to compare, comp just compare strings in lowercase.

bool Playlist::byTitleAscend (Music *a, Music *b) { return comp(a->getTitle(), b->getTitle()); }

Then I try to sort my list with it and it throws an error :/

_musics.sort(byTitleAscend); // ERROR, TODO: why ? 

I hope it's clear enough!

In the documentation they use const & but it's also said that if we don't change the objects it's not necessary.

Error:

MusicReader/playlist.cpp:148: error: no matching function for call to 'std::list(Music*)::sort(unresolved overloaded function type)' _musics.sort(byTitleAscend);

I replaced < by ( because it was not showing.

Answer 1

_musics.sort(byTitleAscend);

line should be in Playlist class scope. If it is not, the line should be

_musics.sort(Playlist::byTitleAscend);

Answer 2

In fact there was several errors, @cokceken was right because I forgot to add the scope and the real problem was that I forgot to scope the comp function too ..

And then without putting the function as static it couldn't work neither, so thanks to @molbdnilo too !