Question

当我尝试编译以下代码时，收到C2672和C2783错误。我无法弄清楚如何解决它。

class Statement
{
public:
    template<typename T, typename ... Args>
    void Bind_All(Args... args)
    {
        std::vector<T> list = { args... };
    }
}

void func()
{
    Statement stmt;
    stmt.Bind_All(1, 2.5, "3");
}

错误C2672：'Statement :: Bind_All'：找不到匹配的重载函数

错误C2783：'void Statement :: Bind_All（Args ...）'：无法推断'T'的模板参数

谢谢！

Answer 1

由于T不是参数的一部分，编译器无法推断出T。你需要明确说明。

Statement stmt;
stmt.Bind_All<int>(1, 2.5, "3");

但是，请注意，这不会起作用，因为行中的“3”cannot be converted to an int`：

std::vector<T> list = { args... };

调用stmt.Bind_All()时，您需要使用合适的参数列表。

Answer 2

以下是如何完成和使用此可变参数模板的示例：

>>> data = """
   lines with tweets here
"""
>>> for line in data.splitlines():
...     print(line.split(" ", 7)[-1])
... 
rt     we're treating one of you lads to this d'struct denim shirt! simply follow &amp; rt to enter
this album is wonderful, i'm so proud of you, i loved this album, it really is the best.    -273
international break is garbage smh. it's boring and your players get injured
get weather updates from the weather channel. 15:27:19
woah what happened to twitter this update is horrible
i've completed the daily quest in paradise island 2!
new post: henderson memorial public library
who's going to  next week?
why so blue?    @ golden bee

或者，如果您想看到实际使用的是不同的类型：

class Statement {
public:
    template <typename T>
    static void Bind_All(T value) {}
    template<typename T,typename ... Args>
    static void Bind_All(T value, Args... args)
    {
        Bind_All(args...);
    }
};

void func()
{
    Statement stmt;
    stmt.Bind_All(1,2.5,"3");
}

int main()
{
    func();
    return 0;
}

在我的系统上，这会产生：

#include <iostream>
#include <typeinfo>

class Statement {
public:
    template <typename T>
    static void Bind_All(T value) 
    {
        std::cout << typeid(value).name() << ":";
        std::cout << value << '\n';
    }

    template<typename T,typename ... Args>
    static void Bind_All(T value, Args... args)
    {
        std::cout << typeid(value).name() << ":";
        std::cout << value << '\n';

        Bind_All(args...);
    }
};

void func()
{
    Statement stmt;
    stmt.Bind_All(1,2.5,"3");
}

int main()
{
    func();
    return 0;
}

尝试使用可变参数编译代码时出错

2 个答案: