Variables PHP

Beenyt $_POST arrayet:

<?php
$var1 = "100";
if(isset($_POST['var1'])){
  $var1 = $_POST['var1'];
}

$var2 = "200";
if(isset($_POST['var2'])){
  $var2 = $_POST['var2'];
}

$var3 = "300";
if(isset($_POST['var3'])){
  $var3 = $_POST['var3'];
}

echo $var1;
echo "<br>";
echo $var2;
echo "<br>";
echo $var3;
?>

<form method="POST" action="save.php">
    <p><input type="text" name="var1" size="20" value="<?php echo $var1; ?> ">
    <input type="submit" value="Ændre var1" name="B1"></p>
</form>

<form method="POST" action="save.php">
    <p><input type="text" name="var2" size="20" value="<?php echo $var2; ?> ">
    <input type="submit" value="Ændre var2" name="B1"></p>
</form>

<form method="POST" action="save.php">
    <p><input type="text" name="var3" size="20" value="<?php echo $var3; ?> ">
    <input type="submit" value="Ændre var3" name="B1"></p>
</form>