In this chapter we will teach you how to open, read, and close a file on the server.
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:
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:
<?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 |
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:
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);
?>
Note: After a call to the fgets() function, the file pointer has moved to the next line.
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:
<?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);
?>
The fgetc() function is identical to the fgets() function, except that it
reads only a single character at a time.
The example below reads the "webdictionary.txt" file character by character, until end-of-file is reached:
<?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.