📂 PHP File Handling – Read, Write, Modify, and Manage Files in PHP

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🧲 Introduction – Why PHP File Handling Matters

File handling is essential in PHP for tasks like reading logs, uploading content, storing form data, and managing assets dynamically. PHP provides a robust set of file system functions to open, read, write, modify, and delete files, making it a critical skill for backend developers.

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📘 Topics Covered

📌 Topic	📄 Description
📁 PHP File Handling Overview	Basic understanding of file operations in PHP
📖 PHP Open / Read / Write / Append	Open a file and perform common file I/O
🗃️ PHP File Existence / Copy / Delete / Download	Check file status and perform basic file manipulations
📊 PHP Handle CSV File	Create and read CSV data with PHP
🔐 PHP File Permissions	Change and manage file permission settings
🗂️ PHP Create Directory	Make new folders using PHP
📃 PHP Listing Files	Read file lists from a directory
🧩 PHP File Inclusion	Include and reuse files dynamically with include() and require()

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📁 PHP File Handling Overview

PHP allows you to interact with the file system using built-in functions like fopen(), fread(), fwrite(), unlink(), and more.

🧠 Key Functions

• fopen() – open a file
• fread() – read a file
• fwrite() – write to a file
• fclose() – close the file

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📖 PHP Open / Read / Write / Append

📌 Opening a File

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

• "r" – open for reading.
• "w" – write only, erases existing content.
• "a" – write only, appends to the end.

📌 Reading File Content

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

📌 Writing to a File

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

📌 Appending Data

$file = fopen("example.txt", "a");
fwrite($file, "\nNew line added!");
fclose($file);

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🗃️ PHP File Existence / Copy / Delete / Download

📌 Check File Exists

if (file_exists("example.txt")) {
    echo "File found!";
}

📌 Copy a File

copy("example.txt", "backup.txt");

📌 Delete a File

unlink("example.txt");

📌 Download a File (Force)

header('Content-Disposition: attachment; filename="example.txt"');
readfile("example.txt");

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📊 PHP Handle CSV File

📌 Create a CSV

$data = [["Name", "Age"], ["Alice", 25], ["Bob", 30]];
$file = fopen("data.csv", "w");

foreach ($data as $row) {
    fputcsv($file, $row);
}
fclose($file);

📌 Read a CSV

$file = fopen("data.csv", "r");
while (($row = fgetcsv($file)) !== false) {
    print_r($row);
}
fclose($file);

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🔐 PHP File Permissions

📌 Change File Permissions

chmod("example.txt", 0644);

• 0644: Read/write for owner, read-only for others.

📌 Check Permissions

echo substr(sprintf('%o', fileperms('example.txt')), -4);

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🗂️ PHP Create Directory

📌 Create Directory

mkdir("myfolder");

📌 Create Directory with Permissions

mkdir("myfolder", 0755, true);  // recursive

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📃 PHP Listing Files

📌 List All Files in a Directory

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

📌 Filter Files

foreach (scandir("myfolder") as $file) {
    if (is_file("myfolder/$file")) {
        echo "$file\n";
    }
}

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🧩 PHP File Inclusion

📌 Include Files

include("header.php");

📌 Require Files (stop on failure)

require("config.php");

✅ Differences:

• include() gives a warning if the file is not found.
• require() gives a fatal error.

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📌 Summary – Recap & Next Steps

With PHP’s powerful file handling capabilities, you can build secure, dynamic, and modular applications that interact with the file system and user uploads efficiently.

🔍 Key Takeaways:

• Master fopen(), fread(), fwrite() for file I/O.
• Use checks like file_exists() and unlink() for robust logic.
• Work with CSVs, directories, and permissions with built-in functions.

⚙️ Real-World Relevance: File handling is crucial in CMS systems, blog platforms, reporting tools, user uploads, and backups.

➡️ Next Up: Explore 🔐 PHP Sessions & Cookies to manage user data between requests.

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❓ FAQs – PHP File Handling

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❓ Can PHP create and delete folders?
✅ Yes, use mkdir() to create and rmdir() to delete directories.

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❓ What is the difference between include and require?
✅ include() gives a warning if the file is missing, while require() throws a fatal error and stops script execution.

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❓ How do I check if a file exists in PHP?
✅ Use file_exists("filename.txt") to verify file presence before reading or writing.

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❓ Can I use PHP to force file downloads?
✅ Yes, use the Content-Disposition header along with readfile().

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❓ How do I read CSV files in PHP?
✅ Use fgetcsv() inside a loop to read CSV rows as arrays.

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