c++ constant function declaration variants?

Question

Are all of the below declarations the same? If so, what is the standard way to declare a constant function?

const SparseMatrix transpose();

SparseMatrix transpo         


        

Answer 1

The first one will return a SparseMatrix that is const and cant be changed.

The second one declares a function that returns a SparseMatrix and assures the function will not change any class variables (assuming it is a member function, otherwise it wouldnt make sense with this deceleration) except for mutable members.

The final one does both.