Description
resource
fopen ( string filename, string mode [, bool use_include_path [, resource zcontext]])
fopen() binds a named resource, specified
by filename, to a stream. If
filename is of the form "scheme://...",
it is assumed to be a URL and PHP will search for a protocol
handler (also known as a wrapper) for that scheme. If no
wrappers for that protocol are registered, PHP will emit
a notice to help you track potential problems in your script
and then continue as though filename
specifies a regular file.
If PHP has decided that filename specifies
a local file, then it will try to open a stream on that file.
The file must be accessible to PHP, so you need to ensure that
the file access permissions allow this access.
If you have enabled safe mode,
or open_basedir further
restrictions may apply.
If PHP has decided that filename specifies
a registered protocol, and that protocol is registered as a
network URL, PHP will check to make sure that
allow_url_fopen is
enabled. If it is switched off, PHP will emit a warning and
the fopen call will fail.
Note:
The list of supported protocols can be found in Appendix L.
Some protocols (also referred to as wrappers) support
context and/or php.ini options.
Refer to the specific page for the protocol in use for a list of options
which can be set. ( i.e. php.ini value
user_agent used by the http wrapper)
For a description of contexts and the
zcontext parameter , refer to Reference CXI, Stream Functions.
Note: Context support was added
with PHP 5.0.0.
The mode parameter specifies the type of access
you require to the stream. It may be any of the following:
Table 1.
A list of possible modes for fopen()
using mode
| mode | Description |
|---|
| '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.
|
| 'x' |
Create and open for writing only; place the file pointer at the
beginning of the file. If the file already exists, the
fopen() call will fail by returning FALSE and
generating an error of level E_WARNING. If
the file does not exist, attempt to create it. This is equivalent
to specifying O_EXCL|O_CREAT flags for the
underlying open(2) system call. This option is
supported in PHP 4.3.2 and later, and only works for local files.
|
| 'x+' |
Create and open for reading and writing; place the file pointer at
the beginning of the file. If the file already exists, the
fopen() call will fail by returning FALSE and
generating an error of level E_WARNING. If
the file does not exist, attempt to create it. This is equivalent
to specifying O_EXCL|O_CREAT flags for the
underlying open(2) system call. This option is
supported in PHP 4.3.2 and later, and only works for local files.
|
Note:
Different operating system families have different line-ending
conventions. When you write a text file and want to insert a line
break, you need to use the correct line-ending character(s) for your
operating system. Unix based systems use \n as the
line ending character, Windows based systems use \r\n
as the line ending characters and Macintosh based systems use
\r as the line ending character.
If you use the wrong line ending characters when writing your files, you
might find that other applications that open those files will "look
funny".
Windows offers a text-mode translation flag ('t')
which will transparently translate \n to
\r\n when working with the file. In contrast, you
can also use 'b' to force binary mode, which will not
translate your data. To use these flags, specify either
'b' or 't' as the last character
of the mode parameter.
The default translation mode depends on the SAPI and version of PHP that
you are using, so you are encouraged to always specify the appropriate
flag for portability reasons. You should use the 't'
mode if you are working with plain-text files and you use
\n to delimit your line endings in your script, but
expect your files to be readable with applications such as notepad. You
should use the 'b' in all other cases.
If you do not specify the 'b' flag when working with binary files, you
may experience strange problems with your data, including broken image
files and strange problems with \r\n characters.
For portability, it is strongly recommended that you always
use the 'b' flag when opening files with fopen().
Again, for portability, it is also strongly recommended that
you re-write code that uses or relies upon the 't'
mode so that it uses the correct line endings and
'b' mode instead.
As of PHP 4.3.2, the default mode is set to binary for all
platforms that distinguish between binary and text mode. If you are
having problems with your scripts after upgrading, try using the
't' flag as a workaround until you have made your
script more portable as mentioned above.
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.
If the open fails, the function returns FALSE and an error of
level E_WARNING is generated. You may use
@ to
suppress this warning.
Example 1. fopen() examples
<?php
$handle = fopen("/home/rasmus/file.txt", "r");
$handle = fopen("/home/rasmus/file.gif", "wb");
$handle = fopen("http://www.example.com/", "r");
$handle = fopen("ftp://user:password@example.com/somefile.txt", "w");
?>
|
|
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.
| Warning |
When using SSL, Microsoft IIS
will violate the protocol by closing the connection without sending a
close_notify indicator. PHP will report this as "SSL: Fatal Protocol Error"
when you reach the end of the data. To workaround this, you should lower your
error_reporting level not to include warnings.
PHP 4.3.7 and higher can detect buggy IIS server software when you open
the stream using the https:// wrapper and will suppress the warning for you.
If you are using fsockopen() to create an ssl:// socket,
you are responsible for detecting and suppressing the warning yourself.
|
Note: When safe mode is enabled, PHP checks whether
the directory in which you are about to operate has the same UID (owner) as the
script that is being executed.
See also Appendix L,
fclose(),
fgets(),
fread(),
fwrite(),
fsockopen(),
file(),
file_exists(),
is_readable(),
stream_set_timeout(), and
popen().
