php - Fatal error: Can't use function return value in write context in -

i have code check if isset mysql data , check int :

<input type="radio" name="lang"  value="1" <?php if(isset(filter_var($__sql__[0]['lang'], filter_validate_int))){         echo ($__sql__[0]['lang'] == 1 ? ' checked="checked"' : '');}?>  /> 

but see error:

fatal error: can't use function return value in write context in  c:\xampp\htdocs\user\modules\editnews.php on line 56 

how can fix error?

it's limitation of php. using isset(), not function, language construct. can use on simple variables, in php versions prior 5.5. see documentation:

prior php 5.5, empty() supports variables; else result in parse error. in other words, following not work: empty(trim($name)). instead, use trim($name) == false.

that means need this:

// we'll check if $__sql__[0]['lang'] exists , // filter_var succeeds. if (isset($__sql__[0]['lang']) && filter_var($__sql__[0]['lang'], filter_validate_int) !== false) {     echo ($__sql__[0]['lang'] == 1 ? ' checked="checked"' : ""); }