You need to escape a character, the backslash, in your array –
$list = array( '$', '\\', '"', '_REQUEST', '_GET', '_POST', '_COOKIE', '_FILES', '_SERVER', '_ENV', 'GLOBALS', '_SESSION', 'toupper' );
And you only need the backslash once in the array.
3
solved Parse error: syntax error, unexpected T_CONSTANT_ENCAPSED_STRING, expecting ‘)’ [closed]