不清楚哪里出问题了，求大佬帮助QAQ

Warning: Cannot modify header information - headers already sent by (output started at F:\Work\test\php_jinjie\session_control.php:3) in F:\Work\test\php_jinjie\session_control.php on line 19

Warning: Cannot modify header information - headers already sent by (output started at F:\Work\test\php_jinjie\session_control.php:3) in F:\Work\test\php_jinjie\session_control.php on line 25

主要报错的地方是：

setcookie('test',time());

header("content-type:text/html;charset=utf-8");