libzmq/doc/zmq_msg_get.adoc

= zmq_msg_get(3)


== NAME
zmq_msg_get - get message property


== SYNOPSIS
*int zmq_msg_get (zmq_msg_t '*message', int 'property');*


== DESCRIPTION
The _zmq_msg_get()_ function shall return the value for the property
specified by the 'property' argument for the message pointed to by the
'message' argument.

The following properties can be retrieved with the _zmq_msg_get()_ function:

*ZMQ_MORE*::
Indicates that there are more message frames to follow after the 'message'.

*ZMQ_SRCFD*::
Returns the file descriptor of the socket the 'message' was read from. This
allows application to retrieve the remote endpoint via 'getpeername(2)'. Be
aware that the respective socket might be closed already, reused even.
Currently only implemented for TCP sockets.

*ZMQ_SHARED*::
Indicates that a message MAY share underlying storage with another copy of
this message.

== RETURN VALUE
The _zmq_msg_get()_ function shall return the value for the property if
successful. Otherwise it shall return `-1` and set 'errno' to one of the
values defined below.


== ERRORS
*EINVAL*::
The requested _property_ is unknown.


== EXAMPLE
.Receiving a multi-frame message
----
zmq_msg_t frame;
while (true) {
    //  Create an empty 0MQ message to hold the message frame
    int rc = zmq_msg_init (&frame);
    assert (rc == 0);
    //  Block until a message is available to be received from socket
    rc = zmq_msg_recv (socket, &frame, 0);
    assert (rc != -1);
    if (zmq_msg_get (&frame, ZMQ_MORE))
        fprintf (stderr, "more\n");
    else {
        fprintf (stderr, "end\n");
        break;
    }
    zmq_msg_close (&frame);
}
----


== SEE ALSO
* xref:zmq_msg_set.adoc[zmq_msg_set]
* xref:zmq_msg_init.adoc[zmq_msg_init]
* xref:zmq_msg_close.adoc[zmq_msg_close]
* xref:zmq.adoc[zmq]


== AUTHORS
This page was written by the 0MQ community. To make a change please
read the 0MQ Contribution Policy at <https://zeromq.org/how-to-contribute/>.