(PHP 4, PHP 5, PHP 7)
getprotobyname — Get protocol number associated with protocol name
$name
   ) : int
   getprotobyname() returns the protocol number
   associated with the protocol name as per
   /etc/protocols.
  
nameThe protocol name.
   Returns the protocol number,  或者在失败时返回 FALSE.
  
Example #1 getprotobyname() example
<?php
$protocol = 'tcp';
$get_prot = getprotobyname($protocol);
if ($get_prot === FALSE) {
    echo 'Invalid Protocol';
} else {
    echo 'Protocol #' . $get_prot;
}
?>