PHP
5 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
<?php
$myfile
= fopen("webdictionary.txt", "r") or die("Unable to
open file!");
echo
fread($myfile,filesize("webdictionary.txt"));
fclose($myfile);
?>
Tip: The
fread() and the fclose() functions will be explained below.
The file may
be opened in one of the following modes:
Modes Description
r Open a file for read only. File pointer
starts at the beginning of the file
w Open a file for write only. Erases the
contents of the file or creates a new file if it doesn't exist. File pointer
starts at the beginning of the file
a Open a file for write only. The existing
data in file is preserved. File pointer starts at the end of the file. Creates
a new file if the file doesn't exist
x Creates a new file for write only. Returns
FALSE and an error if file already exists
r+ Open a file for read/write. File pointer
starts at the beginning of the file
w+ Open a file for read/write. Erases the contents
of the file or creates a new file if it doesn't exist. File pointer starts at
the beginning of the file
a+ Open a file for read/write. The existing data
in file is preserved. File pointer starts at the end of the file. Creates a new
file if the file doesn't exist
x+ Creates a new file for read/write. Returns FALSE
and an error if file already exists
PHP Read
File - fread()
The fread()
function reads from an open file.
The first
parameter of fread() contains the name of the file to read from and the second
parameter specifies the maximum number of bytes to read.
The
following PHP code reads the "webdictionary.txt" file to the end:
fread($myfile,filesize("webdictionary.txt"));
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
$myfile
= fopen("webdictionary.txt", "r");
//
some code to be executed....
fclose($myfile);
?>
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
<?php
$myfile
= fopen("webdictionary.txt", "r") or die("Unable to
open file!");
echo
fgets($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
<?php
$myfile
= fopen("webdictionary.txt", "r") or die("Unable to
open file!");
//
Output one line until end-of-file
while(!feof($myfile))
{
echo fgets($myfile) . "<br>";
}
fclose($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
<?php
$myfile
= fopen("webdictionary.txt", "r") or die("Unable to
open file!");
//
Output one character until end-of-file
while(!feof($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
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