Is always possible to solve a sudoku (that has a unique solution) using only naked pair/triple/quad methods? If not, what about using naked set and hidden set methods combined togheter? I need to know it because I would like to use those methods in a c++ software and I don't wanna use "guessing" because it costs too much in terms of calculations. Is there a solving method that allows me to solve sudokus without guessing?
As tehtmi mentioned in a comment above, you can confirm using Andrew Stewart's solver that these techniques do not suffice for most difficult Sudoku.
But more generally, if your main goal is to write a fast solver (rather than one which models human solving), then don't be afraid of guessing. The fastest solvers for standard Sudoku are usually based on efficient backtracking algorithms with constraint propagation only for hidden singles and locked candidates (i.e., just things that can be implemented really efficiently). Computationally it's a bad trade-off to add more expensive forms of forward inference in an effort to reduce backtracking.
On the question of whether there are solving methods that are guaranteed to work without guessing, the answer is 'yes' if you don't insist that the algorithm be efficient. For example, you can write the rules of Sudoku and the givens of a puzzle as a propositional formula in CNF and then run a prime implicates algorithm like Tison's. Such an algorithm only advances valid consequences, so there's nothing you could call a guess, and it eventually finds all consequences, so it's guaranteed to find your solution. But you'd better get a coffee while it runs. Make that a lot of coffees.
If you want an efficient algorithm that doesn't guess, then you've got to be precise about what you count as a guess since there is range of reasonable definitions arising from different perspectives and tastes.