(PHP 4 >= 4.1.0, PHP 5)
socket_write — Write to a socket
$socket
   , string $buffer
   [, int $length = 0
  ] )
   The function  socket_write() writes to the
   socket from the given
   buffer.
  
socket
     
buffer
     The buffer to be written.
length
     
       The optional parameter length can specify an
       alternate length of bytes written to the socket. If this length is
       greater than the buffer length, it is silently truncated to the length
       of the buffer.
      
   Returns the number of bytes successfully written to the socket or FALSE on failure.
   The error code can be retrieved with
    socket_last_error(). This code may be passed to
    socket_strerror() to get a textual explanation of the
   error.
  
Note:
It is perfectly valid for socket_write() to return zero which means no bytes have been written. Be sure to use the === operator to check for
FALSEin case of an error.
Note:
socket_write() does not necessarily write all bytes from the given buffer. It's valid that, depending on the network buffers etc., only a certain amount of data, even one byte, is written though your buffer is greater. You have to watch out so you don't unintentionally forget to transmit the rest of your data.