链栈

/************************************** 2013.8.12*************************************/#include <iostream>#include <string>using namespace std;#define DEBUG_CONDITION 0template <typename Elem_Type>struct node{Elem_Type e;node<Elem_Type> *next;node(){next=NULL;}node(Elem_Type x):e(x),next(NULL){}~node(){next=NULL;}};template <typename Elem_Type>class Link_Stack{public:Link_Stack():stack_size(0){top_pointer=NULL;}int size(){return stack_size;}void push(Elem_Type x){if(stack_size){node<Elem_Type> *temp = new_node(x);temp->next = top_pointer;top_pointer = temp;}else top_pointer = new_node(x);stack_size++;}void pop(){if(stack_size){node<Elem_Type> *temp = top_pointer->next;delete top_pointer;top_pointer = temp;stack_size--;}else if(DEBUG_CONDITION)cout << "empty_error" << endl;else return;}node<Elem_Type> *top(){return stack_size?top_pointer:NULL;}node<Elem_Type> down(){if(stack_size){Elem_Type temp = top()->e;pop();return make_node(temp);}else {if(DEBUG_CONDITION)cout << "down_error" << endl; return node<Elem_Type>();}}void clear(){if(stack_size){node<Elem_Type> *temp;for(int i=stack_size;i>0;--i){temp = top_pointer->next;delete top_pointer;top_pointer = temp;}}stack_size = 0;top_pointer= NULL;}~Link_Stack(){clear();} friend ostream & operator << (ostream &cout,const Link_Stack<Elem_Type> &LS){cout << "LSstack size = " << LS.stack_size << endl;if(LS.stack_size){node<Elem_Type> *temp = LS.top_pointer; for(int i=LS.stack_size;i>0;--i){cout << "location " << i << " has "<< temp->e << endl;temp = temp->next;}}else cout << "This is empty." << endl;return cout;}private:int stack_size;node<Elem_Type> *top_pointer;node<Elem_Type> make_node(Elem_Type x){return node<Elem_Type>(x);}node<Elem_Type> *new_node(Elem_Type x){return new node<Elem_Type>(x);}};int main(){typedef int TYPE; TYPE d;string order;Link_Stack<TYPE> *LStack = new Link_Stack<TYPE>();while(cin >> order){if(order == "PUSH"){cin >> d;LStack->push(d);}else if(order == "POP"){LStack->pop();}else if(order == "DOWN"){if(LStack->size())cout << "location top is " << LStack->down().e << endl;else cout << "location top is empty." << endl;}else if(order == "CLEAR"){LStack->clear();}else if(order == "SHOW"){cout << *LStack << endl;}else if(order == "TOP"){if(LStack->top())cout << "location top is " << LStack->top()->e << endl;else cout << "location top is empty." << endl;}else break; }return 0;}