c++ - std::pair - 错误:模板参数数量错误

Question

我有一个 std::pair 声明，如下面的代码片段所示，并且 g++ 在第 152 行出现编译错误，提示“错误:模板参数数量错误(1，应该是 2)”。我对这个 std::pair 很陌生，我想知道我做错了什么。所以提到的行号已在下面的代码片段中标记。谢谢。

  std::vector< 
              std::pair<EndPointAddr* requesterServiceAddr, 
                        EndPointAddr*  requestedServiceAddr>* //LINE 152 is HERE
             > mServiceSubscriptionsList; 


  In file included from ServiceRegistrar.hpp:8:0,
                   from ServiceRegistrar.cpp:7:
  ../control_api/ServiceRegistrarAPI.hpp:152:95: error: wrong number of template   arguments (1, should be 2)
  ........
  .......
  ../control_api/ServiceRegistrarAPI.hpp:153:14: error: template argument 1 is invalid
  ../control_api/ServiceRegistrarAPI.hpp:153:14: error: template argument 2 is invalid
  In file included from ../control_api/ServiceRegistrarAPI.cpp:5:0:

Answer 1

std::pair 只需要声明中的类型。

std::vector< 
          std::pair<EndPointAddr*, 
                    EndPointAddr* >* //LINE 152 is HERE
         > mServiceSubscriptionsList;