PHP File Create / Write

Beyond reading files, PHP allows you to create new files and write data to them. This is essential for logging, generating reports, or saving user configurations on the server.

1. Creating a File

The fopen() function is also used to create a file. If you use "w" (write) or "a" (append) on a file that does not exist, PHP will create it for you.

<?php
    $myfile = fopen("testfile.txt", "w") or die("Unable to open file!");
?>

2. Writing to a File - fwrite()

The fwrite() function is used to write to a file. It takes two parameters: the file handle and the string to be written.

<?php
    $myfile = fopen("newfile.txt", "w") or die("Unable to open file!");
    $txt = "John Doe\n";
    fwrite($myfile, $txt);
    $txt = "Jane Doe\n";
    fwrite($myfile, $txt);
    fclose($myfile);
?>

3. Overwriting vs. Appending

Selection of the correct mode is critical to avoid data loss.

Example: Appending to a File

<?php
    $myfile = fopen("log.txt", "a") or die("Unable to open file!");
    $txt = "New login at " . date("H:i:s") . "\n";
    fwrite($myfile, $txt);
    fclose($myfile);
?>

Key Takeaways

• fopen() creates a file if it doesn't exist (in w/a modes).
• fwrite() is the standard function for writing data.
• Use "w" to start fresh and "a" to add to existing data.
• Ensure correct directory permissions for the PHP user.
• Always close file handles to prevent memory bloat.