Waypoint subscription using MAVROS Problem

HI, I want to subscribe waypoint via MAVROS, mavros/missions/waypoints topic, but I have a problem.

When builded the code, the warning happened like below.

warning: format ‘%f’ expects argument of type ‘double’, but argument 8 has type ‘mavros_msgs::WaypointList_<std::allocator >::waypoints_type {aka std::vector<mavros_msgs::Waypoint<std::allocator >, std::allocator<mavros_msgs::Waypoint_<std::allocator > > >}’ [-Wformat=]

I think this problem related to type conversion problem, but I don’t know how to solve this problem :frowning:

I need help…