c++模板缺省值的使用

头文件MyStack_container.h

#pragma once
#include <vector>
#include <deque>

template< typename T, typename CONT = std::vector<T> >
class MyStack {
private:
	CONT elems;//容器

public:
	MyStack();//默认构造

	void push(T const&);//入栈
	void pop();//出栈
	T top() const;//返回栈顶元素
	bool empty() const { return elems.empty(); }//返回栈是否为空

};

#define __MYSTACK_CONTAINER__
#include "MyStack_container.cpp"
           

实现头文件MyStack_container.cpp

#ifdef __MYSTACK_CONTAINER__

//默认构造
template<typename T, typename CONT>
inline
MyStack<T, CONT>::MyStack() {}

//入栈
template<typename T, typename CONT>
inline
void MyStack<T, CONT>::push(T const& elem) {
	elems.push_back(elem);
}

//出栈
template<typename T, typename CONT>
inline
void MyStack<T, CONT>::pop() {
	if (elems.empty())
		throw std::out_of_range("Stack<>::pop() : empty stack");
	elems.pop_back();
}

//返回栈顶元素
template<typename T, typename CONT>
inline
T MyStack<T, CONT>::top() const {
	if (elems.empty())
		throw std::out_of_range("Stack<>::top() : empty stack");
	return elems.back();
}

#endif // __MYSTACK_CONTAINER__

           

测试mian.cpp

#include <iostream>
#include <string>
#include <deque>
#include "MyStack_container.h"


int main()
{
    //模板缺省
    {
        try {
            //定义int栈
            MyStack<int> intStack;//默认用vector

            //定义double栈
            MyStack<double, std::deque<double> > doubleStack;//使用deque容器

            //使用int栈
            intStack.push(7);
            std::cout << "intStack top is " << intStack.top() << std::endl;
            intStack.pop();
            if (intStack.empty())
                std::cout << "intStack is empty";

            //使用double栈
            doubleStack.push(7.777);
            std::cout << "doubleStack top is " << doubleStack.top() << std::endl;
            doubleStack.pop();
            doubleStack.pop();

        }
        catch (const std::exception& ex) {
            std::cerr << "Exception: " << ex.what() << std::endl;
            return EXIT_FAILURE;
        }
    }


}