Using PHP fwrite() to Write Data to Files

fwrite() writes a string to an open file pointer, optionally limiting the number of bytes written.

Parameters: handle – the file resource returned by fopen(); string – the data to write; length – optional maximum number of bytes to write.

Return value: the number of bytes written, or FALSE on error.

Example usage:

<?php
$filename = 'test.txt';
$somecontent = "Add these lines to the file
";
if (is_writable($filename)) {
    $handle = fopen($filename, 'a');
    if (!$handle) {
        echo "Cannot open file $filename";
        exit;
    }
    if (fwrite($handle, $somecontent) === FALSE) {
        echo "Cannot write to file $filename";
        exit;
    }
    echo "Successfully wrote $somecontent to $filename";
    fclose($handle);
} else {
    echo "File $filename is not writable";
}
?>

The script first checks that the target file exists and is writable, opens it in append mode, writes the specified content, reports success or failure, and finally closes the file handle.