setcookie() with Warning: Cannot mod. header. info. - headers already sent by (output started at...)

It is a simple stupid mistake, when I was digging on
setcookie() function, I got error ahead the HTML content:

Warning: Cannot modify header information - headers already sent by (output started at C:\xampp\htdocs\write-cookies.php:1) in C:\xampp\htdocs\write-cookies.php on line 2

And my PHP code is:

<?php
setcookie("myvar", "99", 0, "/", "" 0);
echo "<h1>blablablabla</h1>";
?>

According to the posts from the internet, the crux is the HTML output before the call to this function, but that is not my case:
http://www.webdeveloper.com/forum/showthread.php?74202-RESOLVED-quot-Cannot-modify-header-information-quot http://stackoverflow.com/questions/2658083/setcookie-cannot-modify-header-information-headers-already-sent
Finally, I found the reason here:
PHP setcookie() cannot modify header information 的解决方法

It is because of my incorrect setting on encode format of the file: