isset

I have basically coded a code which populates a list of categories from my database then you are able to select which to delete. I have the issue with the delete code which does not seem to work due to the error: Fatal error: Cannot use isset() on the result of an expression (you can use "null !== expression" instead) in F:\xamppnew\htdocs\650032\admin\delete.php on line 6 The line causing this is: if(isset($_POST['delete_id'] && !empty($_POST['delete_id']))) { deletecategory.php <h3> Delete Category </h3> <?php $result = mysql_query("SELECT * FROM category"); ?> <table> <?php while($row =

I am looking to expand on my PHP knowledge, and I came across something I am not sure what it is or how to even search for it. I am looking at php.net isset code, and I see isset($_GET['something']) ? $_GET['something'] : '' I understand normal isset operations, such as if(isset($_GET['something']){ If something is exists, then it is set and we will do something } but I don't understand the ?, repeating the get again, the : or the ''. Can someone help break this down for me or at least point me in the right direction? It's commonly referred to as 'shorthand' or the Ternary Operator . $test =

This question already has an answer here: JavaScript isset() equivalent 20 answers Is there something in javascript/jQuery to check whether variable is set/available or not? In php, we use isset($variable) to check something like this. thanks. Try this expression: typeof(variable) != "undefined" && variable !== null This will be true if the variable is defined and not null, which is the equivalent of how PHP's isset works. You can use it like this: if(typeof(variable) != "undefined" && variable !== null) { bla(); } JavaScript isset() on PHP JS function isset () { // discuss at: http://phpjs

I have the following array called $fruits : Array ( [response] => Array ( [errormessage] => banana ) [blah] => Array ( [blah1] => blahblah1 [blah2] => blahblah2 [blah3] => blahblah3 [blah4] => blahblah4 ) ) Yet when I do: isset($fruits['response']['errormessage']['orange']) It returns true ! What on earth would cause such a strange behavior and how can I fix this? Thanks! [n] is also a way to access characters in a string: $fruits['response']['errormessage']['orange'] == $fruits['response']['errormessage'][0] // cast to int == b (the first character, at position 0) of 'banana' Use array_key

__unset 触发时机：对象在外部销毁私有或者受保护成员属性的时候调用 　　　　该方法有一个参数：参数就是私有的成员属性名 __isset 触发时机：对象在外部判断私有或者受保护成员属性的时候调用 　　　　该方法有一个参数，参数就是私有的成员属性名 __destruct 析构方法 　　　　触发时机：当对象被销毁的时候自动调用 <?php class Person { public $name; protected $age; private $height; public function __unset($name){ if($name == 'age'){ unset($this->age); } } public function __set($name,$value){ if($name == 'age'){ $this->$name = $value; } } public function __get($name){ if($name == 'age'){ return $this->$name; } } public function __isset($name){ if($name == 'age'){ return isset($this->$name); } } public function __destruct(){ echo '我要去散步了！'; } }

I have (or not) a variable $_GET['myvar'] coming from my query string and I want to check if this variable exists and also if the value corresponds to something inside my if statement: What I'm doing and think is not the best way to do: if(isset($_GET['myvar']) && $_GET['myvar'] == 'something') : do something My question is, exist any way to do this without declare the variable twice? That is a simple case but imagine have to compare many of this $myvar variables. Sadly that's the only way to do it. But there are approaches for dealing with larger arrays. For instance something like this:

I have a function f that takes two parameters ( p1 and p2 ): If for the parameter p2 no value was passed to the function, the value of p1 ^2 should be used instead. But how can I find out within the function, if a value is given or not. The problem is that the variable p2 is not initialized if there was no value. Thus I can't test for p2 being NULL . f <- function(p1, p2) { if(is.null(p2)) { p2=p1^2 } p1-p2 } Is it somehow possible to check if a value for p2 was passed to the function or not? (I could not find an isset() - function or similar things.) You use the function missing() for that. f