chciałbym poniższy kod umieścić wewnątrz string aby następnie zapisać go do pliku. kolejnym etapem będzie zamiana tego pliku w plik ics (kalendarz). w jaki sposób ująć ten kod jako string?

[PHP] pobierz, plaintext 
   <?php
$servername = "";
$username = "";
$password = "";
$dbname = "";
 
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
$conn->set_charset("utf8");
$sql = "SELECT * FROM calendar WHERE id_employee='0100000001'";
$result = $conn->query($sql);
 
if ($result->num_rows > 0) {
 
    echo "BEGIN:VCALENDAR \n";
    echo "PRODID:-//Google Inc//Google Calendar 70.9054//EN \n";
    echo "VERSION:2.0 \n";
    echo "CALSCALE:GREGORIAN \n";
    echo "METHOD:PUBLISH \n";
    echo "X-WR-CALNAME:Calendar \n";
    echo "X-WR-TIMEZONE:Europe/Warsaw \n";
 
    while($row = $result->fetch_assoc()) {
 
        $h_start = $row['h_start'];
        $h_end = $row['h_end'];
        $schedule_notes = $row['schedule_notes'];
 
        echo "BEGIN:VEVENT\n";
        echo "DTSTART:"; //20211227T190000
        echo DateTime::createFromFormat('Y-m-d H:i:s', $h_start)->format('Ymd');
        echo "T";
        echo DateTime::createFromFormat('Y-m-d H:i:s', $h_start)->format('His');
        echo "\n";
        echo "DTEND:"; //20211227T190000
        echo DateTime::createFromFormat('Y-m-d H:i:s', $h_end)->format('Ymd');
        echo "T";
        echo DateTime::createFromFormat('Y-m-d H:i:s', $h_end)->format('His');
        echo "\n";
 
        echo "END:VEVENT\n";
    }
 
    echo "END:VCALENDAR\n";
 
} else {
    echo "no data";
}
$conn->close();
[PHP] pobierz, plaintext 

zamiast echo, to uzywaj zmiennej

$zm .= 'Cos tam';
$zm .= 'Cos tam innego';
$zm .= 'itd itd';

okay, próbuję, ale mam błąd
Warning: Undefined variable $ics in C:\xampp\htdocs\calendar.php on line 134

[PHP] pobierz, plaintext 
if ($result->num_rows > 0) {
 
 
    $icsFilename = 'my_calendar.ics'; // change this according to your needs
    header('Content-Type: text/calendar');
    header("Content-disposition: attachment; filename=\"" .  $icsFilename . "\""); 
 
$ics .= "BEGIN:VCALENDAR \n";
$ics .= "PRODID:-//Google Inc//Google Calendar 70.9054//EN \n";
$ics .= "VERSION:2.0 \n";
$ics .= "CALSCALE:GREGORIAN \n";
$ics .= "METHOD:PUBLISH \n";
$ics .= "X-WR-CALNAME:Pacjenci PŁ \n";
$ics .= "X-WR-TIMEZONE:Europe/Warsaw \n";
 
    while($row = $result->fetch_assoc()) {
 
 
$h_start = $row['h_start'];
$h_end = $row['h_end'];
$imie = $row['imie'];
$nazwisko = $row['nazwisko'];
$schedule_notes = $row['schedule_notes'];
$pesel = $row['pesel'];
$komorka = $row['komorka'];
$uid = substr(sha1(mt_rand()),26,26);
 
 
	$ics .= "BEGIN:VEVENT\n";
 
	$ics .= "SUMMARY:"; //20211227T190000
	$ics .= $imie;
	$ics .= " ";
	$ics .= $nazwisko;
	$ics .= "\n";
 
	$ics .= "DTSTART:"; //20211227T190000
	$ics .= DateTime::createFromFormat('Y-m-d H:i:s', $h_start)->format('Ymd');
	$ics .= "T";
	$ics .= DateTime::createFromFormat('Y-m-d H:i:s', $h_start)->format('His');
	$ics .= "\n";
 
	$ics .= "DTEND:"; //20211227T190000
	$ics .= DateTime::createFromFormat('Y-m-d H:i:s', $h_end)->format('Ymd');
	$ics .= "T";
	$ics .= DateTime::createFromFormat('Y-m-d H:i:s', $h_end)->format('His');
	$ics .= "\n";
 
	$ics .= "UID:"; //7ko43dfm8luc0l4ouv5c16rs10@google.com
	$ics .= $uid;
	$ics .= "@google.com\n";
 
	$ics .= "DESCRIPTION:";
		if (is_null($schedule_notes)) {
			$ics .= "";
		} else {
			$ics .= $schedule_notes;
		}
	$ics .= " ";
 
		if (is_null($pesel)) {
			$ics .= "";
		} else {
			$ics .= $pesel;
		}
	$ics .= " ";
	$ics .= "tel:";
 
		if (is_null($komorka)) {
			$ics .= "";
		} else {
			$ics .= $komorka;
		}
 
	$ics .= " ";
	$ics .= "\n";
 
	$ics .= "CREATED:";
	$ics .= date("Ymd");
	$ics .= "T";
	$ics .= date("His");
	#$ics .= "Z";
	$ics .= "\n";
 
	$ics .= "LAST-MODIFIED:";
	$ics .= date("Ymd");
	$ics .= "T";
	$ics .= date("His");
	#$ics .= "Z";
	$ics .= "\n";
 
	$ics .= "DTSTAMP:";
	$ics .= date("Ymd");
	$ics .= "T";
	$ics .= date("His");
	#$ics .= "Z";
	$ics .= "\n";
 
	$ics .= "LOCATION:";
	$ics .= "\n";
 
	$ics .= "SEQUENCE:0";
	$ics .= "\n";
 
	$ics .= "STATUS:CONFIRMED";
	$ics .= "\n";	
 
	$ics .= "TRANSP:OPAQUE";
	$ics .= "\n";	
 
 
	$ics .= "END:VEVENT\n";
    }
 
	$ics .= "END:VCALENDAR\n";
 
} else {
    $ics .= "brak wyników";
}
#$conn->close();
[PHP] pobierz, plaintext 

Bo na poczatku trzeba te zmienna zadeklarowac np

[PHP] pobierz, plaintext 
$ics = '';
 
$ics .= "BEGIN:VCALENDAR \n";
$ics .= "PRODID:-//Google Inc//Google Calendar 70.9054//EN \n";
[PHP] pobierz, plaintext