php - Un-Definded variable error when not logged on. -

i've error stating "notice: undefined variable: user_data" when no 1 logged in, when logged in, says hello (users name)

here piece of code echos name

"hello, <?php echo $user_data['first_name']; ?>!"

is there anyway can hello, when no user logged in, instead of error message.

thanks.

i feel previous answers not explain happening, i'll try more elaborate here.

what both of them make use of ternary operator, refer "immediate if", can think of following snippet on 1 line:

if ($condition) {     echo "this";   } else {   echo "that"; }

or, ternary operator:

echo $condition ? "this" : "that"; // prints if condition true, if false.

what need solve problem, check if variable set isset, isset checks if variable set, using in if condition, solve error.

example, , answer question:

if (isset($user_data['first_name'])) {    echo 'hello, ' . $user_data['first_name'];  } else {   echo 'hello!'; }

so while ternary operator more convienient use here, not required solve problem, isset in check verify set, required.

that said, both of them solve problem, it's less readable, , may little bit confusing.

EIght