(PHP 5 >= 5.2.0, PHP 7)
DOMNode::C14NFile — Canonicalize nodes to a file
$uri
   [, bool $exclusive = FALSE
   [, bool $with_comments = FALSE
   [, array $xpath
   [, array $ns_prefixes
  ]]]] )Canonicalize nodes to a file.
uriPath to write the output to.
exclusiveEnable exclusive parsing of only the nodes matched by the provided xpath or namespace prefixes.
with_commentsRetain comments in output.
xpathAn array of xpaths to filter the nodes by.
ns_prefixesAn array of namespace prefixes to filter the nodes by.
   Number of bytes written 或者在失败时返回 FALSE