stl类stack

template<class T,class Container=deque<T>> class stack { public: explicit stack(const Container &cnt =Container()); //default constructor ;initializes an empty stack //precondition :none //postcondition :an empty array exist bool empty()const; //determines whether the stack is empty //precondition :none //postcondition :returns true if the stack is emtpy //otherwise returns false size_type size()const; //determinate the size of the stack.the return type //size_type is an integral type //precondition :none //postcondition :returns the number of items that //are currents in the stack T &top(); //returns a reference to the top of the stack //precondition None; //postcondition :the item remains on the stack; void pop(); //removes the top item in the stack //precondition :none //postcondition :the items most recently added //is removed from the stack void push(); //adds an items to the top of the stack //precondition :none //postcondition :Item x is the top of the stack };