第五章

一、为了保证T::const_iterator不被看作类的成员变量，使用typename修饰表明它是模板类里的类型。

#include <iostream>  
#include <vector> 

template<typename T>
void printcoll(T const& coll)
{
    typename T::const_iterator pos;
    typename T::const_iterator end(coll.end());

    for (pos = coll.begin(); pos != end; ++pos)
    {
        std::cout << *pos << ' ';
    }

    std::cout << std::endl;
}

int main(int argc, char** argv[])
{
    // 测试printcoll
    std::vector<int> intVector;
    intVector.push_back(1);
    intVector.push_back(2);
    intVector.push_back(3);
    intVector.push_back(4);

    printcoll(intVector);
    return 0;
}

 

二、使用.template来区分大于号(>)和小于号(<)

#include <iostream>
#include <bitset>
#include <memory>
#include <string>

template<int N>
void printBitset(std::bitset<N> const&bs)
{
    std::cout << bs.template to_string<char, std::char_traits<char>, std::allocator<char>>();
}

int main(int argc, char** argv)
{
    std::bitset<8> bs;
    bs = (long)131;

    printBitset<8>(bs);
    return 0;
}

三、模板赋值预算

#pragma once
#include <iostream>
#include <deque>

template <typename T>
class Stack
{
private:
    std::deque<T> elems;
public:
    void push(T const &elem);
    void pop();
    T top() const;
    bool empty() const {
        return elems.empty();
    }

    template <typename T2>
    Stack<T>& operator=(Stack<T2> const &);
};

template<typename T>
inline void Stack<T>::push(T const & elem)
{
    elems.push_back(elem);
}

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

template<typename T>
inline T Stack<T>::top() const
{
    if (elems.empty()) {
        throw std::out_of_range("Stack<>::top(): empty stack");
    }
    return elems.back();
}

template <typename T>
template <typename T2>
Stack<T> &Stack<T>::operator=(Stack<T2> const &op2)
{
    if ((void *)this == (void *)&op2)
        return *this;

    Stack<T2> tmp(op2);
    elems.clear();
    while (!tmp.empty()) {
        elems.push_front(tmp.top());
        tmp.pop();
    }
    return *this;
}

测试用例：

#include <iostream>
#include <bitset>
#include <memory>
#include <string>
#include <vector>
#include "stack5dec1.hpp"

template<int N>
void printBitset(std::bitset<N> const&bs)
{
    std::cout << bs.template to_string<char, std::char_traits<char>, std::allocator<char>>();
}

int main(int argc, char** argv)
{
    std::bitset<8> bs;
    bs = (long)131;

    printBitset<8>(bs);

    Stack<int> intStack;
    Stack<float> floatStack;

    intStack.push(5);
    intStack.push(6);

    std::cout << std::endl;
    while (!intStack.empty()) {
        std::cout << intStack.top() << std::endl;;
        intStack.pop();
    }

    floatStack.push(1.0);
    floatStack.push(2.1);

    intStack = floatStack;

    std::cout << std::endl;
    while (!intStack.empty()) {
        std::cout << intStack.top() << std::endl;;
        intStack.pop();
    }
    

    return 0;
}