Topic: PHP Basics – Part 8 of 10: Working with Files and Directories

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1. Introduction to File Handling in PHP

• PHP allows you to create, read, write, append, and delete files on the server.

• You can also manage directories, check if a file exists, and more.

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2. Opening a File

Use the fopen() function:

$handle = fopen("example.txt", "r");

• "r" means read-only. Other modes include:

| Mode | Description |
| ------ | -------------------------------- |
| "r" | Read-only |
| "w" | Write-only (truncates file) |
| "a" | Append |
| "x" | Create & write (fails if exists) |
| "r+" | Read & write |

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3. Reading from a File

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

echo $content;

• fread() reads the entire file based on its size.

• Always use fclose() to release system resources.

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4. Writing to a File

$handle = fopen("newfile.txt", "w");
fwrite($handle, "Hello from PHP file writing!");
fclose($handle);

• If the file doesn't exist, it will be created.

• If it exists, it will be overwritten.

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5. Appending to a File

$handle = fopen("log.txt", "a");
fwrite($handle, "New log entry\n");
fclose($handle);

• "a" keeps existing content and adds to the end.

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6. Reading Line by Line

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

• feof() checks for end of file.

• fgets() reads a single line.

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7. Checking If File Exists

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

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8. Deleting a File

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

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9. Working with Directories

• Create a directory:

mkdir("myfolder");

• Check if a directory exists:

if (is_dir("myfolder")) {
    echo "Directory exists!";
}

• Delete a directory:

rmdir("myfolder"); // Only works if empty

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10. Scanning a Directory

$files = scandir("myfolder");
print_r($files);

• Returns an array of file and directory names.

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11. Uploading Files

This is a common use case when working with files in PHP.

HTML Form:

<form action="upload.php" method="post" enctype="multipart/form-data">
  <input type="file" name="uploadedFile">
  <input type="submit" value="Upload">
</form>

upload.php:

if ($_FILES["uploadedFile"]["error"] === 0) {
    $target = "uploads/" . basename($_FILES["uploadedFile"]["name"]);
    move_uploaded_file($_FILES["uploadedFile"]["tmp_name"], $target);
    echo "Upload successful!";
}

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12. Summary

• PHP provides powerful tools for file and directory operations.

• You can manage content, upload files, read/write dynamically, and handle directories with ease.

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Exercise

• Create a PHP script that:

* Checks if a file named data.txt exists
* If it does, reads and prints its contents
* If not, creates the file and writes a welcome message

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