C++ 11 可变模板参数的两种展开方式

#include <iostream>
#include <string>
#include <stdint.h>

template<typename T>
T Sum(T t)
{
    std::cout << t << " = ";
    return t;
}
template<typename T, typename... Args>
T Sum(T head, Args...args)
{
    std::cout << head << " + ";
    return head + Sum(args...);
}

template<typename T>
void PrintArg(T t)
{
    std::cout << t << " ";
}
template<typename... Args>
void Expand(Args... args)
{
    std::initializer_list<int32_t> {(PrintArg(args), )...};
    std::cout << std::endl;
}

int32_t main()
{
    std::cout << Sum(, , , ) << std::endl;
    Expand(, , , );
    std::cin.get();
    return ;
}

效果:

 +  +  +  =