Introduction: Why PHP File Handling Matters

File handling is a core aspect of backend development. Whether you're reading logs, processing form data, generating reports, or uploading files, you'll need to interact with files on the server.

PHP provides a rich set of built-in file system functions that allow developers to create, open, read, write, append, rename, and delete files. This makes PHP extremely powerful for building dynamic, data-driven websites.

In this article, you'll learn step-by-step how to handle files in PHP safely and efficiently.

Basic Concepts in PHP File Handling

Common PHP File Handling Functions

Step-by-Step: PHP File Handling Operations

1. Opening a File with fopen()

$file = fopen("example.txt", "r"); // 'r' = read mode

Modes Explained:

2. Reading a File with fread()

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

echo $content;

3. Writing to a File with fwrite()

$file = fopen("log.txt", "w");
fwrite($file, "This is a log entry.\n");
fclose($file);

This overwrites any existing content in log.txt.

4. Appending to a File with a Mode

$file = fopen("log.txt", "a");
fwrite($file, "New log entry at " . date("Y-m-d H:i:s") . "\n");
fclose($file);

5. Using file_get_contents() and file_put_contents() (Simplified)

// Read entire file into a string
$data = file_get_contents("example.txt");

// Write a string into a file
file_put_contents("output.txt", "Hello, world!");

These are cleaner alternatives to fopen() for simple use cases.

6. Deleting a File with unlink()

if (file_exists("delete_me.txt")) {
    unlink("delete_me.txt");
    echo "File deleted.";
} else {
    echo "File not found.";
}

✅ Full Working Example

<?php
$file = "data.txt";

// Write to the file
file_put_contents($file, "This is line 1\n");

// Append to the file
file_put_contents($file, "This is line 2\n", FILE_APPEND);

// Read and display contents
if (file_exists($file)) {
    $contents = file_get_contents($file);
    echo "File Contents:\n" . $contents;
} else {
    echo "File not found.";
}
?>

Tips & Common Pitfalls

✅ Best Practices

• Always close files using fclose() to free resources.

• Use file_exists() to avoid errors before accessing files.

• Prefer file_put_contents()/file_get_contents() for quick operations.

• Use try-catch with Exception handling in advanced scenarios (custom error handling).

• Set proper file permissions (read/write) on the server.

❌ Common Mistakes

• Forgetting to check if a file exists before reading it.

• Using 'w' mode without realizing it deletes existing content.

• Not handling file permission issues (especially on Linux servers).

• Assuming fopen() always succeeds—always check the return value.

File Handling Function Comparison

Summary: Best Practices for PHP File Handling

• PHP provides powerful and flexible file handling capabilities.

• Use appropriate file modes (r, w, a, etc.) based on your intent.

• Use simplified functions (file_get_contents, file_put_contents) when possible.

• Always check if the file exists before operating on it.

• Be mindful of file permissions and server environment.