C++如何区分容器模板和 native 类型

Question

我有以下问题:

template<class T>
void set(std::string path, const T data)
{
   stringstream ss;
   ss << data << std::endl;
   write(path, ss.str();
}

template<class T>
void set(std::string path, const T data)
{
    std::stringstream ss;
    for(typename T::const_iterator it = data.begin(); it < data.end(); ++it)
    {
       ss << *it;
       if(it < data.end() -1 )
          ss << ", ";
    }
    ss << std::endl;
    write(path, ss.str());
}

我收到以下错误:

error: ‘template<class T> void myclass::set(std::string, T)’ cannot be overloaded
error: with ‘template<class T> void myclass::set(std::string, T)’

有没有办法在模板中区分容器类型和其他类型？

Answer 1

使用特征:

#include <type_traits>

template <typename T>
typename std::enable_if<is_container<T>::value>::type
set (std::string const & path, T const & container)
{
    // for (auto const & x : container) // ...
}


template <typename T>
typename std::enable_if<!is_container<T>::value>::type
set (std::string const & path, T const & data)
{
    std::ostringstream oss;
    oss << data;
    write(path, oss.str());
}

您可以在 pretty printer code 中找到合适的特征.