c++ pointer to string question

Posted on 2012-09-06
Medium Priority
Last Modified: 2012-09-06
zmq::message_t topic;
 std::string secID =  md.get_securityID() ;   // value is "123"
 std::cout << &secID << std::endl;
 memcpy( topic.data() , &secID, 20 );
 m_socket->send( topic,  ZMQ_SNDMORE );

sends passes encoded text possible a memory location while:

 zmq::message_t topic;
 std::string secID =  md.get_securityID() ;  
 std::cout << &secID << std::endl;
 memcpy( topic.data() , "123", 3 );
 m_socket->send( topic,  ZMQ_SNDMORE );

The hard-coded string is correctly passed as "123" in the topic message.

memcpy  arguments are  ( pointer, pointer, length)

How do I pass the value of md.get_securityID not the address in the topic message?
Question by:mcgilljd
LVL 86

Accepted Solution

jkr earned 2000 total points
ID: 38373940
You'd use 'string::c_str()', e.g.

memcpy( topic.data() , secID.c_str(), secID.legth() );

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Author Closing Comment

ID: 38373972
Works great!

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