迭代器不会遍历整个地图

Question

I have the following function:

   void send_sequence_to_device( std::map<const string_t,device_t*> &msg2device_p, std::vector<response_t>& result_list, ushort num_attempts)
    {
        cout<<"sarit enter to send_seq_device"<<endl;
        std::map<const string_t, device_t*>::iterator msg_itf;
        for( msg_itf=msg2device_p.begin(); msg_itf!=msg2device_p.end(); msg_itf++ )
        {
            cout<<"sarit enter to seq "<<msg_itf->first<<endl;
        }
    }

I call this function by another function:

 void node_layer_manager_t::calc_ts_job_function()
    {
        vector<response_t> res;
        map<const string_t, device_t*> getRegMsg={{"get_node_ts_est",&tx},{"get_node_ts_est",&rx},{"get_tx_num_clk_ts",&tx}};
        cout<< "sarit ts clk function nlm first"<<endl;
        send_sequence_to_device(getRegMsg,res);
    }

i can see that the loop iterate only 2 instead of 3. The output is:

sarit enter to seq get_node_ts_est

sarit enter to get_tx_num_clk_ts

While I expect for:

sarit enter to seq get_node_ts_est

sarit enter to seq get_node_ts_est

sarit enter to get_tx_num_clk_ts

Answer 1

A std::map does not allow duplicate keys.

Two of your values have the same key, hence only one of them will make it into the map.

Use std::multimap instead of std::map , if you need duplicate keys.