C++类模板与函数模板基础详细讲解

template <typename T>
int compare(const T &v1, const T &v2)
{
    if (v1 < v2)
        return -1;
    if (v2 < v1)
        return 1;
    return 0;
}

 int res = compare(3, 4);
    cout << "compare(3,4) res is " << res << endl;
    vector<int> v1 = {1, 3, 5};
    vector<int> v2 = {2, 4};
    res = compare(v1, v2);
    cout << "compare(v1, v2) res is " << res << endl;

template <typename T, typename U>
int printData(const T &t, const U &u)
{
    cout << "t is " << t << endl;
    cout << "u is " << u << endl;
}

 printData(3.4, "hello world");

template <unsigned N, unsigned M>
int compareArray(const char (&p1)[N], const char (&p2)[M])
{
    return strcmp(p1, p2);
}

 res = compareArray("hello zack", "nice to meet u");
    cout << "compareArray("
         << "hello zack "
         << ", nice to meet u"
         << ") res is " << res << endl;

//定义模板类型的blob
template <typename T>
class Blob
{
public:
    typedef T value_type;
    typedef typename std::vector<T>::size_type size_type;
    //构造函数
    Blob()
    {
        data = make_shared<std::vector<T>>();
    }
    Blob(std::initializer_list<T> il)
    {
        data = make_shared<std::vector<T>>(il);
        // for (const T &m : il)
        // {
        //     data->push_back(m);
        // }
    }
    // Blob 中元素数目
    size_type size() const { return data->size(); }
    bool empty() const { return data->empty(); }
    //添加和删除元素
    void push_back(const T &t) { data->push_back(t); }
    //移动版本的push_back
    void push_back(const T &&t) { data->push_back(std::move(t)); }
    //删除元素
    void pop_back();
    //元素访问
    T &back();
    T &operator[](size_type i);
private:
    std::shared_ptr<std::vector<T>> data;
    //校验数据是否有效
    void check(size_type i, const std::string &msg) const;
};

template <typename T>
void Blob<T>::check(size_type i, const std::string &msg) const
{
    if (i >= data->size())
        throw std::out_of_range(msg);
}
template <typename T>
void Blob<T>::pop_back()
{
    if (data->empty())
    {
        return;
    }
    data->pop_back();
}
template <typename T>
T &Blob<T>::back()
{
    return data->back();
}
template <typename T>
T &Blob<T>::operator[](size_type i)
{
    check(i, "index out of range");
    return (*data)[i];
}

void use_classtemp()
{
    Blob<int> ia;
    Blob<int> ia2 = {0, 1, 2, 3, 5};
    Blob<string> ia3 = {"hello ", "zack", "nice"};
    for (size_t i = 0; i < ia2.size(); i++)
    {
        ia2[i] = i * i;
    }
    for (size_t i = 0; i < ia2.size(); i++)
    {
        cout << ia2[i] << endl;
    }
    for (size_t i = 0; i < ia3.size(); i++)
    {
        string_upper(ia3[i]);
    }
    for (size_t i = 0; i < ia3.size(); i++)
    {
        cout << ia3[i] << endl;
    }
    const auto &data = ia3.back();
    cout << data << endl;
    ia3.pop_back();
    const auto &data2 = ia3.back();
    cout << data2 << endl;
}