PHP File Open/Read/Close
In this chapter we will teach you how to open, read, and close a file on the server.
PHP Open File — fopen()
A better method to open files is with the fopen() function. This function gives you more options than the readfile() function.
We will use the text file, «webdictionary.txt», during the lessons:
AJAX = Asynchronous JavaScript and XML
CSS = Cascading Style Sheets
HTML = Hyper Text Markup Language
PHP = PHP Hypertext Preprocessor
SQL = Structured Query Language
SVG = Scalable Vector Graphics
XML = EXtensible Markup Language
The first parameter of fopen() contains the name of the file to be opened and the second parameter specifies in which mode the file should be opened. The following example also generates a message if the fopen() function is unable to open the specified file:
Example
$myfile = fopen(«webdictionary.txt», «r») or die(«Unable to open file!»);
echo fread($myfile,filesize(«webdictionary.txt»));
fclose($myfile);
?>
Tip: The fread() and the fclose() functions will be explained below.
The file may be opened in one of the following modes:
| Modes | Description |
|---|---|
| r | Open a file for read only. File pointer starts at the beginning of the file |
| w | Open a file for write only. Erases the contents of the file or creates a new file if it doesn’t exist. File pointer starts at the beginning of the file |
| a | Open a file for write only. The existing data in file is preserved. File pointer starts at the end of the file. Creates a new file if the file doesn’t exist |
| x | Creates a new file for write only. Returns FALSE and an error if file already exists |
| r+ | Open a file for read/write. File pointer starts at the beginning of the file |
| w+ | Open a file for read/write. Erases the contents of the file or creates a new file if it doesn’t exist. File pointer starts at the beginning of the file |
| a+ | Open a file for read/write. The existing data in file is preserved. File pointer starts at the end of the file. Creates a new file if the file doesn’t exist |
| x+ | Creates a new file for read/write. Returns FALSE and an error if file already exists |
PHP Read File — fread()
The fread() function reads from an open file.
The first parameter of fread() contains the name of the file to read from and the second parameter specifies the maximum number of bytes to read.
The following PHP code reads the «webdictionary.txt» file to the end:
PHP Close File — fclose()
The fclose() function is used to close an open file.
It’s a good programming practice to close all files after you have finished with them. You don’t want an open file running around on your server taking up resources!
The fclose() requires the name of the file (or a variable that holds the filename) we want to close:
PHP Read Single Line — fgets()
The fgets() function is used to read a single line from a file.
The example below outputs the first line of the «webdictionary.txt» file:
Example
$myfile = fopen(«webdictionary.txt», «r») or die(«Unable to open file!»);
echo fgets($myfile);
fclose($myfile);
?>
Note: After a call to the fgets() function, the file pointer has moved to the next line.
PHP Check End-Of-File — feof()
The feof() function checks if the «end-of-file» (EOF) has been reached.
The feof() function is useful for looping through data of unknown length.
The example below reads the «webdictionary.txt» file line by line, until end-of-file is reached:
Example
$myfile = fopen(«webdictionary.txt», «r») or die(«Unable to open file!»);
// Output one line until end-of-file
while(!feof($myfile)) echo fgets($myfile) . «
«;
>
fclose($myfile);
?>
PHP Read Single Character — fgetc()
The fgetc() function is used to read a single character from a file.
The example below reads the «webdictionary.txt» file character by character, until end-of-file is reached:
Example
$myfile = fopen(«webdictionary.txt», «r») or die(«Unable to open file!»);
// Output one character until end-of-file
while(!feof($myfile)) echo fgetc($myfile);
>
fclose($myfile);
?>
Note: After a call to the fgetc() function, the file pointer moves to the next character.
Complete PHP Filesystem Reference
For a complete reference of filesystem functions, go to our complete PHP Filesystem Reference.
fopen
fopen() binds a named resource, specified by filename , to a stream.
Parameters
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 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 Supported Protocols and Wrappers. 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. (e.g. php.ini value user_agent used by the http wrapper).
On the Windows platform, be careful to escape any backslashes used in the path to the file, or use forward slashes.
The mode parameter specifies the type of access you require to the stream. It may be any of the following:
| 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; otherwise it has the same behavior as ‘w’ . |
| ‘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. In this mode, fseek() has no effect, writes are always appended. |
| ‘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. In this mode, fseek() only affects the reading position, writes are always appended. |
| ‘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. |
| ‘x+’ | Create and open for reading and writing; otherwise it has the same behavior as ‘x’ . |
| ‘c’ | Open the file for writing only. If the file does not exist, it is created. If it exists, it is neither truncated (as opposed to ‘w’ ), nor the call to this function fails (as is the case with ‘x’ ). The file pointer is positioned on the beginning of the file. This may be useful if it’s desired to get an advisory lock (see flock() ) before attempting to modify the file, as using ‘w’ could truncate the file before the lock was obtained (if truncation is desired, ftruncate() can be used after the lock is requested). |
| ‘c+’ | Open the file for reading and writing; otherwise it has the same behavior as ‘c’ . |
| ‘e’ | Set close-on-exec flag on the opened file descriptor. Only available in PHP compiled on POSIX.1-2008 conform systems. |
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 (Mac OS Classic) used \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 is ‘b’ . You can 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 old versions of notepad. You should use the ‘b’ in all other cases.
If you specify the ‘t’ 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.
Note:
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.
Note: The mode is ignored for php://output , php://input , php://stdin , php://stdout , php://stderr and php://fd stream wrappers.
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.