i'm working in client zone, and i want to make wordpress user can submit form once, and show html code if he submitted before. can you guys help me to do that?

i tried to do this, but it dosen't work.

global $current_user;
wp_get_current_user() ;
$client_usercurrent = $current_user->user_login;
$myArr = array();

if (in_array($client_usercurrent, $myArr)) {
    echo "YYYYYYYYYYYYYYYYYYYYYYYYYYYes";
}

$myArr() = $client_usercurrent;

/* end submit  */
/* if current user exsits in $myarr we should hide the form */

if (in_array($client_usercurrent, $myArr)) {
    echo "YYYYYYYYYYYYYYYYYYYYYYYYYYYes";
}

thanks