PHP File Handling

In PHP, File handling is the process of interacting with files on the server, such as reading files, writing to a file, creating new files, or deleting existing ones. File handling is essential for applications that require the storage and retrieval of data, such as logging systems, user-generated content, or file uploads.

Types of File Operations in PHP

Several types of file operations can be performed in PHP:

• Reading Files: PHP allows you to read data from files either entirely or line by line.
• Writing to Files: You can write data to a file, either overwriting existing content or appending to the end.
• File Metadata: PHP allows you to gather information about files, such as their size, type, and last modified time.
• File Uploading: PHP can handle file uploads via forms, enabling users to submit files to the server.

Common File Handling Functions in PHP

• fopen() - Opens a file
• fclose() - Closes a file
• fread() - Reads data from a file
• fwrite() - Writes data to a file
• file_exists() - Checks if a file exists
• unlink() - Deletes a file

Opening and Closing Files

Before you can read or write to a file, you need to open it using the fopen() function, which returns a file pointer resource. Once you're done working with the file, you should close it using fclose() to free up resources.

<?php

// Open the file in read mode
$file = fopen("gfg.txt", "r"); 

if ($file) {
    echo "File opened successfully!";
    fclose($file); // Close the file
} else {
    echo "Failed to open the file.";
}

?>

File Modes in PHP

Files can be opened in any of the following modes:

• "w" – Opens a file for writing only. If the file does not exist, then a new file is created, and if the file already exists, then the file will be truncated (the contents of the file are erased).
• "r" – File is open for reading only.
• "a" – File is open for writing only. The file pointer points to the end of the file. Existing data in the file is preserved.
• "w+" – Opens file for reading and writing both. If the file does not exist, then a new file is created, and if the file already exists, then the contents of the file are erased.
• "r+" – File is open for reading and writing both.
• "a+" – File is open for write/read. The file pointer points to the end of the file. Existing data in the file is preserved. If the file is not there, then a new file is created.
• "x" – New file is created for write only.

Reading from Files

There are two ways to read the contents of a file in PHP. These are -

1. Reading the Entire File

You can read the entire content of a file using the fread() function or the file_get_contents() function.

<?php

$file = fopen("gfg.txt", "r");
$content = fread($file, filesize("gfg.txt"));

echo $content;
fclose($file);

?>

2. Reading a File Line by Line

You can use the fgets() function to read a file line by line.

<?php
  
$file = fopen("gfg.txt", "r");

if ($file) {
    while (($line = fgets($file)) !== false) {
        echo $line . "<br>";
    }
    fclose($file);
}

?>

Writing to Files

You can write to files using the fwrite() function. It writes data to an open file in the specified mode.

<?php
  
// Open the file in write mode
$file = fopen("gfg.txt", 'w');

if ($file) {
    $text = "Hello world\n";
    fwrite($file, $text);
  	fclose($file);
}

?>

Deleting Files

Use the unlink() function to delete the file in PHP.

<?php

if (file_exists("gfg.txt")) {
    unlink("gfg.txt");
    echo "File deleted successfully!";
} else {
    echo "File does not exist.";
}

?>