The return appears to be the size in bytes of the data written to the socket, or -1 on failure (this could be because of non blocking)
stream_socket_sendto — Sends a message to a socket, whether it is connected or not
$flags= 0 [, string
Sends the specified
data through the
The socket to send
The data to be sent.
The value of
flags can be any combination
of the following:
||Process OOB (out-of-band) data.|
The address specified when the socket stream was created will be used
unless an alternate address is specified in
If specified, it must be in dotted quad (or [ipv6]) format.
Returns a result code, as an integer.
Exemplo #1 stream_socket_sendto() Example
/* Open a socket to port 1234 on localhost */
$socket = stream_socket_client('tcp://127.0.0.1:1234');
/* Send ordinary data via ordinary channels. */
fwrite($socket, "Normal data transmit.");
/* Send more data out of band. */
stream_socket_sendto($socket, "Out of Band data.", STREAM_OOB);
/* Close it up */