regular expression; problem with '-' character

Hi, Could someone be kind enough to have a look at this regular expression and perhaps tell me why is returns false when a '-' character is included in the $center string? if (eregi("^[a-zA-Z0-9!@#\$%^&\*\(\),/.//<>\?;':\"~`_\+\|\-\\\t\n\ ]*$", $center)) { return true; } else { return false; } This regular expression is just for making sure that the input contains only characters that are available on a standard (American-English) keyboard i.e. if the string contains a '©' it will return false. Maybe there's a better way to do this without using regular expressions? Thanks very much in advance for any help. - Best regards, Lee