
        typedef int Truth;
        const int TRUE = 1;
        const int FALSE = 0;
        const int size = 100;   // constant integer, kind of like a macro

        class Stack {		// Stack of integers
        public:                 // these members are public
                Stack()                 { sp = 0; }
                void push( int x)       { elt[sp++] = x; }
                int pop()               { return elt[--sp]; }
                Truth isempty()         { return sp <= 0; }
                Truth isfull()          { return sp >= size; }
        private:                // these (data) members are private
                int sp;         // sp 'points' to next available slot
                int elt[size];
        };

