Cookies are not setting via wordpress plugin code

i am writing a plugin, where i am setting a cookie. When i set cookie using php method it show warning.

Warning: Cannot modify header information - headers already sent by (output started at

if i use wordpress action, for setting cookie its not working. I have use this in my theme functions.php file its working fine but not working in plugin code.

Here are code samples:

Using php method

setcookie( 'sm_js_cookie', 1, time()+3600*24*100,'/');

Using wordpres action:

function set_newuser_cookie() {

    setcookie( 'sm_js_cookie', $_SERVER['REMOTE_ADDR'], time()+3600*24*100,'/');

}

add_action( 'init', 'set_newuser_cookie');

Please help me to find its solution.

via Chebli Mohamed