If filename begins with "http://" (not case sensitive), an HTTP 1.0 connection is opened to the specified server, the page is requested using the HTTP GET method, and a file pointer is returned to the beginning of the body of the response. A 'Host:' header is sent with the request in order to handle name-based virtual hosts.
As of PHP 4.3.0, if you have compiled in support for OpenSSL, you may use "https://" to open an HTTP connection over SSL.
Note that the file pointer allows you to retrieve only the body of the response; to retrieve the HTTP response header you need to be using PHP 4.0.5 or later; The headers will be stored in the $http_response_header variable. As of PHP 4.3.0, the header information can be retrieved using the file_get_wrapper_data().
HTTP connections are read-only; you cannot write data or copy files to an HTTP resource.
Versions prior to PHP 4.0.5 do not handle HTTP redirects. Because of this, directories must include trailing slashes.
If filename begins with "ftp://" (not case sensitive), an ftp connection to the specified server is opened and a pointer to the requested file is returned. If the server does not support passive mode ftp, this will fail. You can open files for either reading or writing via ftp (but not both simultaneously). If the remote file already exists on the ftp server and you attempt to open it for writing, this will fail. If you need to update existing files over ftp, use ftp_connect().
If filename is one of "php://stdin", "php://stdout", or "php://stderr", the corresponding stdio stream will be opened. (This was introduced in PHP 3.0.13; in earlier versions, a filename such as "/dev/stdin" or "/dev/fd/0" must be used to access the stdio streams.)
If filename begins with anything else, the file will be opened from the filesystem, and a file pointer to the file opened is returned.
If the open fails, the function returns FALSE.
mode may be any of the following:
'r' - Open for reading only; place the file pointer at the beginning of the file.
'r+' - Open for reading and writing; place the file pointer at the beginning of the file.
'w' - Open for writing only; place the file pointer at the beginning of the file and truncate the file to zero length. If the file does not exist, attempt to create it.
'w+' - Open for reading and writing; place the file pointer at the beginning of the file and truncate the file to zero length. If the file does not exist, attempt to create it.
'a' - Open for writing only; place the file pointer at the end of the file. If the file does not exist, attempt to create it.
'a+' - Open for reading and writing; place the file pointer at the end of the file. If the file does not exist, attempt to create it.
Megjegyzés: The mode may contain the letter 'b'. This is useful only on systems which differentiate between binary and text files (i.e. Windows. It's useless on Unix). If not needed, this will be ignored.
The optional third use_include_path parameter can be set to '1' or TRUE if you want to search for the file in the include_path, too.
The optional fourth zcontext is used for specifying tuning parameters and callbacks.
If you are experiencing problems with reading and writing to files and you're using the server module version of PHP, remember to make sure that the files and directories you're using are accessible to the server process.
On the Windows platform, be careful to escape any backslashes used in the path to the file, or use forward slashes.
See also fclose(), fgets(), fsockopen(), file(), file_exists(), is_readable(), socket_set_timeout(), and popen().