zstr(3)
CZMQ Manual - CZMQ/2.2.1
Name
zstr - sending and receiving strings
Synopsis
// Receive C string from socket. Caller must free returned string using
// zstr_free(). Returns NULL if the context is being terminated or the
// process was interrupted.
CZMQ_EXPORT char *
zstr_recv (void *socket);
// Receive C string from socket, if socket had input ready. Caller must
// free returned string using zstr_free. Returns NULL if there was no input
// waiting, or if the context was terminated. Use zctx_interrupted to exit
// any loop that relies on this method.
CZMQ_EXPORT char *
zstr_recv_nowait (void *socket);
// Send a C string to a socket, as a frame. The string is sent without
// trailing null byte; to read this you can use zstr_recv, or a similar
// method that adds a null terminator on the received string.
CZMQ_EXPORT int
zstr_send (void *socket, const char *string);
// Send a C string to a socket, as zstr_send(), with a MORE flag, so that
// you can send further strings in the same multi-part message.
CZMQ_EXPORT int
zstr_sendm (void *socket, const char *string);
// Send a formatted string to a socket. Note that you should NOT use
// user-supplied strings in the format (they may contain '%' which
// will create security holes).
CZMQ_EXPORT int
zstr_sendf (void *socket, const char *format, ...);
// Send a formatted string to a socket, as for zstr_sendf(), with a
// MORE flag, so that you can send further strings in the same multi-part
// message.
CZMQ_EXPORT int
zstr_sendfm (void *socket, const char *format, ...);
// Send a series of strings (until NULL) as multipart data
// Returns 0 if the strings could be sent OK, or -1 on error.
CZMQ_EXPORT int
zstr_sendx (void *socket, const char *string, ...);
// Receive a series of strings (until NULL) from multipart data.
// Each string is allocated and filled with string data; if there
// are not enough frames, unallocated strings are set to NULL.
// Returns -1 if the message could not be read, else returns the
// number of strings filled, zero or more. Free each returned string
// using zstr_free().
CZMQ_EXPORT int
zstr_recvx (void *socket, char **string_p, ...);
// Free a provided string, and nullify the parent pointer. Safe to call on
// a null pointer.
CZMQ_EXPORT void
zstr_free (char **string_p);
// Self test of this class
CZMQ_EXPORT int
zstr_test (bool verbose);
Description
The zstr class provides utility functions for sending and receiving C strings across ØMQ sockets. It sends strings without a terminating null, and appends a null byte on received strings. This class is for simple message sending.
Example
From zstr_test method
zctx_t *ctx = zctx_new ();
assert (ctx);
void *output = zsocket_new (ctx, ZMQ_PAIR);
assert (output);
zsocket_bind (output, "inproc://zstr.test");
void *input = zsocket_new (ctx, ZMQ_PAIR);
assert (input);
zsocket_connect (input, "inproc://zstr.test");
// Send ten strings, five strings with MORE flag and then END
int string_nbr;
for (string_nbr = 0; string_nbr < 10; string_nbr++)
zstr_sendf (output, "this is string %d", string_nbr);
zstr_sendx (output, "This", "is", "almost", "the", "very", "END", NULL);
// Read and count until we receive END
string_nbr = 0;
for (string_nbr = 0;; string_nbr++) {
char *string = zstr_recv (input);
if (streq (string, "END")) {
zstr_free (&string);
break;
}
zstr_free (&string);
}
assert (string_nbr == 15);
zctx_destroy (&ctx);
See also
Authors
The CZMQ manual was written by Pieter Hintjens<moc.xitami|hp#moc.xitami|hp>.
Resources
Main web site: http://czmq.zeromq.org/
Report bugs to the ØMQ development mailing list: <gro.qmorez.stsil|ved-qmorez#gro.qmorez.stsil|ved-qmorez>
Copyright
Copyright (c) 1991-2014 iMatix and Contributors. License LGPLv3+: GNU LGPL 3 or later <http://gnu.org/licenses/lgpl.html>. This is free software: you are free to change it and redistribute it. There is NO WARRANTY, to the extent permitted by law. For details see the files COPYING and COPYING.LESSER included with the CZMQ distribution.