PHP Write File – Complete Guide

PHP provides multiple ways to write to a file. The most common functions are:

fwrite()
file_put_contents()

Writing to a File Using fwrite()

Step 1: Open a File for Writing

$file = fopen("example.txt", "w"); // Open file in write mode

if ($file) {
    fwrite($file, "Hello, this is a test file!");
    fclose($file);
    echo "File written successfully!";
} else {
    echo "Error opening file.";
}

✅ "w" mode creates a new file or overwrites an existing one.
✅ Always close the file with fclose() after writing.

Append Data to a File Using fwrite()

$file = fopen("example.txt", "a"); // Open file in append mode

if ($file) {
    fwrite($file, "\nNew content added.");
    fclose($file);
    echo "Content appended successfully!";
} else {
    echo "Error opening file.";
}

✅ "a" mode appends data instead of overwriting.

Writing to a File Using file_put_contents()

file_put_contents("example.txt", "This is a new line.");

✅ This function is simpler than fwrite().
✅ Overwrites existing content.

To append instead of overwriting:

file_put_contents("example.txt", "\nAppending a new line.", FILE_APPEND);

Handling Errors When Writing a File

$file = "example.txt";

if (is_writable($file)) {
    file_put_contents($file, "Writing safely.");
    echo "File written successfully!";
} else {
    echo "Cannot write to file.";
}

✅ Always check if the file is writable before writing.

Best Practices for Writing Files in PHP

🔹 Use file_put_contents() for simple writes.
🔹 Use fwrite() for large files or appending data.
🔹 Ensure the file has the correct permissions.
🔹 Close files after writing (fclose()).

Complete PHP Write File Code Example

$file = "example.txt";

if ($handle = fopen($file, "w")) {
    fwrite($handle, "Hello, PHP File Writing!");
    fclose($handle);
    echo "File written successfully!";
} else {
    echo "Error: Unable to open file.";
}