? File Handling in PHP

File handling in PHP allows you to create, read, write, append, and delete files on the server. It's useful for storing user data, logs, reports, and more.

? Basic File Operations

1. Open a File – fopen()

$handle = fopen("file.txt", "r"); // r = read

2. Write to a File – fwrite()

$file = fopen("example.txt", "w");fwrite($file, "Hello, world!");fclose($file);

3. Read from a File – fread()

$file = fopen("example.txt", "r");$content = fread($file, filesize("example.txt"));fclose($file);echo $content;

4. Read Line-by-Line – fgets()

$file = fopen("example.txt", "r");while (!feof($file)) {    echo fgets($file) . "<br>";}fclose($file);

5. Check if File Exists – file_exists()

if (file_exists("example.txt")) {    echo "File exists!";} else {    echo "File does not exist!";}

6. Delete a File – unlink()

if (file_exists("old.txt")) {    unlink("old.txt");    echo "File deleted.";}

7. Quick Write – file_put_contents()

file_put_contents("data.txt", "This is quick content.");

8. Quick Read – file_get_contents()

$data = file_get_contents("data.txt");echo $data;

? Example: Simple Guestbook (Write & Read)

// write.php$name = $_POST['name'];file_put_contents("guests.txt", $name . "\n", FILE_APPEND);echo "Thanks, $name!";

// read.php$guests = file("guests.txt");foreach ($guests as $guest) {    echo htmlspecialchars($guest) . "<br>";}

? Tips for File Handling

• Always fclose() your files.

• Use file_exists() before reading or deleting.

• Use htmlspecialchars() when displaying user input from a file.

• Be cautious with file permissions on the server.