To check if a folder or a file is in use, the function is_dir() or is_file() can be used.The scandir function is an inbuilt function that returns an array of files and directories of a specific directory. It lists the files and directories present inside the path specified by the user.For example$scan = scandir('myFolder'); foreach($scan as $file) {    if (!is_dir("myFolder/$file")) {       echo $file.'';    } }OutputList of files and directories inside the path specified (if any)The directory ‘myFolder’ is scanned using the ‘scandir’ function and the files and directories inside it are listed out. The ‘foreach’ ... Read More

When the backslash \ does not escape the terminating quote of the string or even create a valid escape sequence (in double quoted strings), then the below code can be used to produce one backslash −Example Live Demo$string = 'abc\def'; print($string);OutputThis will produce the following output −abc\defExample Live Demo$string = "abc\def"; print($string);OutputThis will produce the following output −abc\def

The domain name can be validated using the below code in PHP −Example Live Demo $domain_name = 'https://tutorialspoint.com' is_valid_domain_name($domain_name)OutputThis will produce the following output −$domain_name = 'https://tutorialspoint.com' is_valid_domain_name($domain_name)In the above code, the ‘preg_match’ function is used to match the domain_name passed as an argument to the user-defined function ‘is_valid_domain_name’.

To install Imagick or Imagemagick on windows, follow the below mentioned procedure −Check the permissions on the .dll file. This will make sure that the Apache user has read access to the file.It is better to change the permission of the [PHP]/extension directory.In order to change the permission, follow the below steps −Right click on the file(s) or folder(s)Select "Properties"Select the "Security" tabClick on "Edit" button.Change the permission of user to Full Control.

The memory_get_usage() function can be caked before and after allocating memory to the class created.class MyBigClass {    var $allocatedSize;    var $allMyOtherStuff; } function AllocateMyBigClass() {    $before = memory_get_usage();    $ret = new MyBigClass;    $after = memory_get_usage();    $ret->allocatedSize = ($after - $before);    return $ret; }Output will be the memory of object with respect to the environment setup.

In PHP version 5.3, methods of objects in array can be called using the below code −$props = array_map(function($obj){ return $obj->getProp(); }, $objs);This will be slower than a ‘for’ loop since it invokes one function for every element −function map($obj) {    return $obj->getProperty(); } $props = array_map('map', $objs);Alternatively, for PHP versions before 5.3, the below code can be used −function map($obj) {    return $obj-> getProperty (); } $props = array_map('map', $objs); }The getProperty function will be called on all the objects and the specific property is displayed. Alternative −function encode_data($val){    if(is_array($val)){       return $val = ... Read More

The short answer is no. POST/GET values are never null. The best they can be is an empty string, which can then be converted to null/'NULL' −Example Live Demoif ($_POST['value'] === '') {    $_POST['value'] = null; } echo'Null assigned';OutputThis will produce the following output −Null assigned

PHP doesn't support friend-like declarations. It can be simulated in PHP5 using the __get and __set methods and by inspecting a backtrace for the allowed friend classes. But this type of coding practice is considered to be clumsy −class sample_friend {    private $__friends = array('My_Friend', 'Other_Friend');    public function __get($key)    {       $trace = debug_backtrace();       if(isset($trace[1]['class']) && in_array($trace[1]['class'], $this->__friends)) {          return $this->$key;       }       // __get() code goes here       trigger_error('Cannot access private property ' . __CLASS__ . '::$' . $key, E_USER_ERROR); ... Read More

The .ini files from the main php,ini file can’t be included. Instead, while compiling PHP, the line--with-config-file-scan-dir=PATH                                                can be added.The ‘PATH’ in the above line refers to the location where the configuration file is to be scanned.During compile time, PHP will look for each and every .ini file in that specific directory, apart from searching in the normal php.ini file.

The memory_get_usage function can be used to track the memory usage. The ‘malloc’ function is not used for every block required, instead a big chunk of system memory is allocated and the environment variable is changed and managed internally.The two different types of memory usages are −The memory required by the engine from OS (the real usage)The amount of memory that was actually used by the application (internal usage)The above mentioned memory usage can be tracked using memory_get_usage(). This function returns both real and actual memory used depending on our requirement.For example: if we are looking at specific code snippets, ... Read More