Compile Error: Cannot use isset() on the result of an expression
From documentation:
isset() only works with variables as passing anything else will result in a parse error.
You're not directly passing a variable to isset()
. So you need to calculate the value first, assign it to a variable, and then pass that to isset()
.
For example, what you're doing at the moment is something like:
if(isset($something === false)) { } // throws a parse error, because $something === false is not a variable
What you need to do instead is:
$something = false;
if(isset($something)) { ... }
Fatal error: Cannot use isset() on the result of an expression
As mentioned in the comments (and the error message), you cannot pass the result of an expression to isset
.
You can use multiple isset calls, or reverse the logic of your if/else block and pass multiple parameters to isset, which i think is the cleanest solution:
//true if both are set
if(isset($size, $color)) {
$style = 'font-size : ' . $size . ';color:' . $color;
}else{
$style = '';
}
You can clean this up a little further by setting the default value first, thus avoiding the need for an else section:
$style = '';
if(isset($size, $color)) {
$style = 'font-size : ' . $size . ';color:' . $color;
}
You could even use a ternary, though some people find them harder to read:
$style = isset($size, $color) ? 'font-size : ' . $size . ';color:' . $color : '';
Fatal error: Cannot use isset, use null expression instead
if(isset($userEmail = $_POST["email"]) && $userEmail = $_POST["email"] != ""){
Here, you are assigning it to a variable and then checking isset
all in a single call. Split it up into separate calls:
- check if it is set
- check if it is not an empty string
- validate it against the built-in email validator
- assign it to a variable
Likely should be
if(isset($_POST["email"]) && $_POST["email"] != "") {
if(filter_var($_POST["email"], FILTER_VALIDATE_EMAIL)) {
...
$userEmail = $_POST["email"];
...
isset() on the result of an expression
I'd use the null coalescing operator ??
(https://www.php.net/manual/en/language.operators.comparison.php#language.operators.comparison.coalesce)
return [
'description' => $this->field($content, 'description') ?? '',
//...
];
Fatal error: Cannot use isset, use null expression
Do you mean
if ( isset($_GET['reply_id'], $_GET['reply_user']) ) {
// code here
}
Fatal error in if stament
Just change the condition to:
if(isset($_REQUEST['userid']) && $_REQUEST['userid'] > $user_hack)
isset
tells is a variable is set, while this statement may be true or false, on which you cannot call isset
function.
Until you check if(isset($_REQUEST['userid']))
, you cannot assign it to $userid
variable.
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