Fatal error: Cannot use isset() on the result of an expression (you can use “null !== expression” instead)

问题

if(isset($_GET['a'] or $_GET['b'])){
  echo "ok";
}else{
  echo "no";
 }

i have two var for one condition when isset $_GET['a'] or $_GET['b']
always echo ok either echo no

回答1:

isset takes only one input not two

it should be

if(isset($_GET['a']) OR isset($_GET['b']))
{
echo 'ok';
}
else
{
echo 'nope';
}

来源：https://stackoverflow.com/questions/32061024/fatal-error-cannot-use-isset-on-the-result-of-an-expression-you-can-use-nul