如果选中复选框，则选中Echo

if this is my checkbox

<input type="checkbox" name="Filter[]" value="Steak" id="Filter"/>

and if checkbox is checked var_export returns me

["Filter"]=> array(1) { [0]=> string(7) "Steak" 

how do I echo "checked=checked" if checkbox is checked?

$checked = in_array('Steak',$_POST['Filter']) ? ' checked="checked"' : '';
echo '<input type="checkbox" name="Filter[]" value="Steak" id="Filter"'.$checked.'/>';

What you need is in_array(), this will check whether that value exists in the array, if your array contains the value, the function will return true and you can simply echo out the checked attribute

if (in_array('YOUR_VALUE_HERE', $arr)) {
   echo 'checked="checked"';
}

You can also make a function passing value and array as parameter and returning the value from the function.

<?php // Check if the box was sent.
  $checked = "";
  $status = (isset($_REQUEST['status']));
if ($status == 'checked' )  
{
  $status = 1;
  $checked = 'checked="checked"';
}
else
{
  $status = 0;
}
  echo $status; 
  echo <<<END
 <form action="" method="post">
<input type="checkbox" name="status" $checked /> Testbox<br />
<input type="submit" onclick="return showDiv();"/>
</form>
END;
?>

I think this might solve your problem

$checked = in_array('Steak',$_POST['Filter']) ? ' checked="checked"' : ''; echo '';