isset

问题 I have an upload form with a file to be uploaded. The issue I have is that even when no file is uploaded the if(isset($_FILES)) OR if(!empty($_FILES)) still passes as successful: $_FILES = $HTTP_POST_FILES; if($_POST['type'] == 'photo' && isset($_FILES)){ // returns true even if no file is uploaded. What am I missing! } 回答1: Being a superglobal, $_FILES is presumably always set, regardless whether an uploaded file exists or not. Check for the file upload(s) you would expect and look at the

问题 I have an upload form with a file to be uploaded. The issue I have is that even when no file is uploaded the if(isset($_FILES)) OR if(!empty($_FILES)) still passes as successful: $_FILES = $HTTP_POST_FILES; if($_POST['type'] == 'photo' && isset($_FILES)){ // returns true even if no file is uploaded. What am I missing! } 回答1: Being a superglobal, $_FILES is presumably always set, regardless whether an uploaded file exists or not. Check for the file upload(s) you would expect and look at the

问题 Is there a concise way to check if a variable is set, and then echo it without repeating the same variable name? Instead of this: <?php if(!empty($this->variable)) { echo '<a href="', $this->variable, '">Link</a>'; } ?> I'm thinking about something in the lines of this C-style pseudocode: <?php echo if(!empty($this->variable, '<a href="', %s, '">Link</a>')); ?> PHP has sprintf, but it doesn't quite do what I was hoping for. If course I could make a method/function out of it, but surely there

问题 How to check if array variable $a = array('a'=>1, 'c'=>null); is set and is null. function check($array, $key) { if (isset($array[$key])) { if (is_null($array[$key])) { echo $key . ' is null'; } echo $key . ' is set'; } } check($a, 'a'); check($a, 'b'); check($a, 'c'); Is it possible in PHP to have function which will check if $a['c'] is null and if $a['b'] exist without "PHP Notice: ..." errors? 回答1: Use array_key_exists() instead of isset() , because isset() will return false if the

问题 I mean... I "set" it to NULL. So isset($somethingNULL) == true? 回答1: bool isset ( mixed $var [, mixed $var [, $... ]] ) Determine if a variable is set and is not NULL. If a variable has been unset with unset(), it will no longer be set. isset() will return FALSE if testing a variable that has been set to NULL . Also note that a NULL byte ("\0") is not equivalent to the PHP NULL constant. Return values Returns TRUE if var exists and has value other than NULL, FALSE otherwise. From the manual.

问题 I am not able to get this to work correctly!! I have a view.php page that uses a variable of 'ID' to retrieve db info. So my url is like this: /view.php?id=23 I am trying to get it to "redirect" the user to the home page if they erase the "23" part of the url.. ? so when you visit /view.php?id= It should : if(isset($_GET['id']) == "") { header('Location: /'); exit; } Works if I visit /view.php 回答1: Try using empty(): if(empty($_GET['id'])) { header('Location: /'); exit; } 回答2: Another way: if

问题 How to check if a multidimensional array item is set in JS? w[1][2] = new Array; w[1][2][1] = new Array; w[1][2][1][1] = 10; w[1][2][1][2] = 20; w[1][2][1][4] = 30; How to check if w[1][2][1][3] is set? Solution with if (typeof w[1][2][1][3] != 'undefined') doesn't work. I don't want to use an Object instead of Array. 回答1: You are not checking the previous array elements existence before checking its children as the children elements cant exist if the parent doesnt if( typeof(w) != 'undefined

问题 Is there any speed difference between if (isset($_POST['var'])) or if ($_POST['var']) And which is better or are they the same? 回答1: It is a good practice to use isset for the following reasons: If $_POST['var'] is an empty string or "0" , isset will still detect that the variable exists. Not using isset will generate a notice. 回答2: They aren't the same. Consider a notional array: $arr = array( 'a' => false, 'b' => 0, 'c' => '', 'd' => array(), 'e' => null, 'f' => 0.0, ); Assuming $x is one

问题 Is there any speed difference between if (isset($_POST['var'])) or if ($_POST['var']) And which is better or are they the same? 回答1: It is a good practice to use isset for the following reasons: If $_POST['var'] is an empty string or "0" , isset will still detect that the variable exists. Not using isset will generate a notice. 回答2: They aren't the same. Consider a notional array: $arr = array( 'a' => false, 'b' => 0, 'c' => '', 'd' => array(), 'e' => null, 'f' => 0.0, ); Assuming $x is one

问题 I'm trying to make functions like empty() and isset() work with data returned by methods. What I have so far: abstract class FooBase{ public function __isset($name){ $getter = 'get'.ucfirst($name); if(method_exists($this, $getter)) return isset($this->$getter()); // not working :( // Fatal error: Can't use method return value in write context } public function __get($name){ $getter = 'get'.ucfirst($name); if(method_exists($this, $getter)) return $this->$getter(); } public function __set($name