# stream_socket_pair

(PHP 5 >= 5.1.0)

stream_socket_pair — Creates a pair of connected, indistinguishable socket streams

### Description

array stream_socket_pair ( int `$domain` , int `$type` , int `$protocol` )

stream_socket_pair() creates a pair of connected, indistinguishable socket streams. This function is commonly used in IPC (Inter-Process Communication).

### Parameters

`domain`

  The protocol family to be used: `STREAM_PF_INET`, `STREAM_PF_INET6` or `STREAM_PF_UNIX`

`type`

  The type of communication to be used: `STREAM_SOCK_DGRAM`, `STREAM_SOCK_RAW`, `STREAM_SOCK_RDM`, `STREAM_SOCK_SEQPACKET` or `STREAM_SOCK_STREAM`

`protocol`

  The protocol to be used: `STREAM_IPPROTO_ICMP`, `STREAM_IPPROTO_IP`, `STREAM_IPPROTO_RAW`, `STREAM_IPPROTO_TCP` or `STREAM_IPPROTO_UDP`

> Note: Please consult the Streams constant list for further details on each constant.

### Return Values

Returns an array with the two socket resources on success, or `FALSE` on failure.

### Examples

Example#1 A stream_socket_pair() example

This example shows the basic usage of stream_socket_pair() in Inter-Process Comunication.

`<?php
$sockets = stream_socket_pair(STREAM_PF_UNIX, STREAM_SOCK_STREAM, STREAM_IPPROTO_IP);
$pid = pcntl_fork();
if ($pid == -1) {
die('could not fork');
} else if ($pid) {
/* parent */
fclose($sockets[0]);
fwrite($sockets[1], "child PID: $pid\n");
echo fgets($sockets[1]);
fclose($sockets[1]);
} else {
/* child */
fclose($sockets[1]);
fwrite($sockets[0], "message from child\n");
echo fgets($sockets[0]);
fclose($sockets[0]);
}
?>`

The above example will output something similar to:

    child PID: 1378
    message from child