WordPress Notice "Undefined Index"

I am getting following notice in WordPress

Notice: Undefined index: _wpnonce in /var/www/vhosts/abc.biz/php/func.php on line 338

Any soluti开发者_如何学JAVAon? Thanks for help

I found the solution, have to use isset() to check _wpnonce value, before comparing it.

if ( isset($_POST['_wpnonce']) && $_POST['_wpnonce'] = '123456789' ) {}

Thanks.