学步园

#include <vector><br /> #include <stdexcept><br /> #include <iostream><br /> #include <deque><br /> #include <cstdlib><br /> //std::vector<T> 是CONT的缺省值(缺省模板实参)<br /> template <typename T, typename CONT = std::vector<T> ><br /> class Stack {<br /> private:<br /> CONT elems; // elements</p> <p>public:<br /> void push(T const&); // push element<br /> void pop(); // pop element<br /> T top() const; // return top element<br /> bool empty() const { // return whether the stack is empty<br /> return elems.empty();<br /> }<br /> };</p> <p>template <typename T, typename CONT><br /> void Stack<T,CONT>::push (T const& elem)<br /> {<br /> elems.push_back(elem); // append copy of passed elem<br /> }</p> <p>template <typename T, typename CONT><br /> void Stack<T,CONT>::pop ()<br /> {<br /> if (elems.empty()) {<br /> throw std::out_of_range("Stack<>::pop(): empty stack");<br /> }<br /> elems.pop_back(); // remove last element<br /> }</p> <p>template <typename T, typename CONT><br /> T Stack<T,CONT>::top () const<br /> {<br /> if (elems.empty()) {<br /> throw std::out_of_range("Stack<>::top(): empty stack");<br /> }<br /> return elems.back(); // return copy of last element<br /> }<br /> int main()<br /> {<br /> try {<br /> // stack of ints:<br /> Stack<int> intStack;</p> <p> // stack of doubles which uses a std::deque<> to manage the elements<br /> Stack<double,std::deque<double> > dblStack;</p> <p> // manipulate int stack<br /> intStack.push(7);<br /> std::cout << intStack.top() << std::endl;<br /> intStack.pop();</p> <p> // manipulate double stack<br /> dblStack.push(42.42);<br /> std::cout << dblStack.top() << std::endl;<br /> dblStack.pop();<br /> dblStack.pop();<br /> }<br /> catch (std::exception const& ex) {<br /> std::cerr << "Exception: " << ex.what() << std::endl;<br /> return EXIT_FAILURE; // exit program with ERROR status<br /> }<br /> }</p> <p>/*<br /> 程序执行结果:<br /> 7<br /> 42.42<br /> Exception: Stack<>::pop(): empty stack<br /> 对于函数模板和类模板，模板参数并不局限于类型，普通值也可以作为模板参数<br /> 对于非类型模板参数，你不能使用浮点数，class 类型的对象和内部链接对象（string）作为实参</p> <p>*/