C++ strcat(template版本)

 template<unsigned N, unsigned M>
 inline std::shared_ptr<char> strcat(const char (&p1)[N], const char (&p2)[M])
 {
     std::shared_ptr<char> s1(new char[N]);
     char s2[M];
     std::strcpy(s1.get(), p1);
     std::strcpy(s2, p2);
     std::strcat(s1.get(), s2);
     return s1;
 };