PHP File Handling

File handling is an essential component of every web application. You frequently need to open and process a file for various activities.

Create, read, upload, and modify files are all supported by PHP.

Take caution to manipulate files! , You must be very careful while manipulating files.

If you do anything poorly, you may do a lot of damage. The most common mistakes are to modify a false file, overload a hard disc with waste data, and accidentally delete the contents of a file.

PHP provides many useful functions to work with files contents (open, close, read, write) and directories.

Reads a file and publishes it to the output buffer with the readfile() method.

Note:- The readfile() method returns the number of bytes reads on success.

Let's assume we have a text file on the server called "demo.txt" that looks like this :

Welcome To
PHP File Tutorial
by Simmanchith.com

Example :- The following is the PHP code for reading the file and writing it to the output buffer:

<?php
echo readfile("demo.txt");
?>

Output :-

If all you want to do is open a file and read its contents, the readfile() method is beneficial.

File Modes are very important thing to work with any files. It tells what type of action should be performed while reading or writing on the files.

One of the following modes can be used to open the file:

Using the fopen() function to open files is a better option. This method provides additional options than readfile().

Syntax:-

fopen("filename", "filemode");

The name of the file to be opened is the first parameter of fopen(), and the second argument defines the mode in which the file should be opened. If the fopen() function fails to open the supplied file, then the die() function will display the message "Unable to open file!".

Example :-

<?php
$myfile = fopen("demo.txt", "r") or die("Unable to open file!");
?>

Note:- In the above example, We just opened a file and we did not do any file operations like read or write.

An open file can be closed with the fclose() function.

After finishing it, it is a great programming habit to close all files. You don't want an open file to operate on the resource of your server!

Syntax:-

fclose("filename");

The filename (or a variable containing the filename) we wish to close by fclose() function.

<?php
$myfile = fopen("demo.txt", "r");
// some code to be executed....
fclose($myfile);
?>

The fread() method reads data from a file that is currently open.

The filesize() return file size (number of bytes available) of a given file.

Syntax:

fread(file_pointer, "number_of_bytes_to_read");

• file_pointer - The file referenced by fopen() function
• number_of_bytes_to_read - How many bytes to read from the specified file.

Example 1:- The PHP code below reads the entire text from "demo.txt" file.

<?php
$myfile = fopen("demo.txt", "r") or die("Unable to open file!");
$data = fread($myfile, filesize("demo.txt"));
fclose($myfile);
echo $data;
?>

Output:-

Example 2:- The PHP code below reads only 10 characters from "demo.txt" file.

<?php
$myfile = fopen("demo.txt", "r") or die("Unable to open file!");
$data = fread($myfile, 10);
fclose($myfile);
echo $data;
?>

Output:-

The fgets() method is used to read a single line from the file.

Example :- The first two line of the "demo.txt" file is printed in the example below :

<?php
$myfile = fopen("demo.txt", "r") or die("Unable to open file!");
echo fgets($myfile) . "<br />";
echo fgets($myfile);
fclose($myfile);
?>

Output :-

Note :- The file pointer is shifted on to the next line after a call to the fgets() method.

The feof() function is used check whether a file pointer reached end of the file or not.

The feof() function determines whether or not the "end-of-file" (EOF) condition has been met.

It is very useful when you want to read all contents of a file line by line. For looping through data of uncertain length, the feof() method is handy.

Example :- The following example reads line by line the file "demo.txt" until end of file.

<?php
$myfile = fopen("demo.txt", "r") or die("Unable to open file!");
// Print a line number
$no = 1;
// Output one line until end-of-file
while(!feof($myfile)) {
  echo $no . ". " . fgets($myfile) . "<br />";
}
fclose($myfile);
?>

Output :-

When reading a single character from a file, the fgetc() method is utilised.

Example :- The following example reads first three characters of the "demo.txt" file.

<?php
$myfile = fopen("demo.txt", "r") or die("Unable to open file!");
echo getc($myfile) . "<br />";
echo getc($myfile) . "<br />";
echo getc($myfile);
fclose($myfile);
?>

Output :-

Note:- You can use feof() function with a loop to read all contents of file by character by character.

A file is also created using the fopen() method. Although it may appear to be a bit perplexing, in PHP, a file is created using the same function that opens files.

If you have used fopen() on a file not available, it will be created once the file is opened to write (w) or append (a) mode.

Example :- In the following example you create a new "testfile.txt" file. The PHP code file is generated in the same directory :

$myfile = fopen("testfile.txt", "w")

If you're experiencing trouble getting this code to execute, make sure you've given your PHP file permission to write data to the hard disc.

Writing to a file is done with the fwrite() function.

Syntax:-

fwrite(file_pointer, data_to_write);

• file_pointer - The file referenced by fopen() method tell where to write the data.
• data_to_write - What data to writtern to the specified file.

Example :- The following example creates a new file named "newfile.txt".

<?php
$myfile = fopen("newfile.txt", "w") or die("Unable to open file!");
fwrite($myfile, "Hello\n");
fwrite($myfile, "World!");
fclose($myfile);
?>

Note:- You can use multiple times fwrite() function to write data to file.

The newfile.txt does not exist and it will created by fopen() function.

This is what the "newfile.txt" file looks like when we open it :-

The w file mode is used to overwrite the content of a file.

Now that newfile.txt includes some information, and if you write again some data to the file it will delete the existing data and write the new one.

Example :- We'll open our old file "newfile.txt" and add some new data to it in the example below:

<?php
$myfile = fopen("newfile.txt", "w") or die("Unable to open file!");
fwrite($myfile, "Welcome");
fclose($myfile);
?>

Both "Hello" and "World!" have vanished from the "newfile.txt" file, leaving only the data we just typed:

The a file mode is used to append the content to the end of file..

Example :- We'll open our old file "newfile.txt" with a (append mode) and add some new data to it in the example below:

<?php
$myfile = fopen("newfile.txt", "a") or die("Unable to open file!");
fwrite($myfile, " To\n");
fwrite($myfile, "Simmanchtih.com");
fclose($myfile);
?>

Note:- The newly added data is appended to end of the file