查找域名、由名字查找某个熟知的端口、由名字查

      
        struct
      
      
         servent{

    
      
      
        char
      
         *s_name;     
      
        /*
      
      
         official service name 
      
      
        */
      
      
        char
      
       **s_aliases;   
      
        /*
      
      
         other aliases 
      
      
        */
      
      
        char
      
           s_port;       
      
        /*
      
      
         prot ofr this service 
      
      
        */
      
      
        char
      
         *s_proto;     
      
        /*
      
      
         protocol to use 
      
      
        */
      
      
        

};




      
      
        struct
      
       servent *
      
        sptr;

sptr 
      
      = getservbyname(
      
        "
      
      
        smtp
      
      
        "
      
      ,
      
        "
      
      
        tcp
      
      
        "
      
      ));
    

      
        struct
      
      
         protoent{

    
      
      
        char
      
          *
      
        pname;

    
      
      
        char
      
        **
      
        p_aliases;

    
      
      
        char
      
      
              p_proto;

};




      
      
        struct
      
       protoent *
      
        pptr;

pptr
      
      =getprotobyname(
      
        "
      
      
        udp
      
      
        "
      
      );
    

      
        struct
      
      
         hostent{

    
      
      
        char
      
           *
      
        h_name;

    
      
      
        char
      
         **
      
        h_aliases;

    
      
      
        char
      
      
               h_addrtype;

    
      
      
        char
      
             h_length;                   
      
        /*
      
      
         address length 
      
      
        */
      
      
        char
      
         **h_addr_list;               
      
        /*
      
      
         list of addresses 
      
      
        */
      
      
        

};




      
      
        struct
      
       hostent *
      
        htpr;


      
      
        char
      
       *str=
      
        "
      
      
        dlut.edu.cn
      
      
        "
      
      
        ;

htpr 
      
      = gethostbyname(str);