PHP file_exists()

file_exists() function checks whether a file or directory exist or not. It returns TRUE if exists, otherwise FALSE.
   bool file_exists(str file or dir)

<?PHP
   $file = "/usr/test.txt";
   if (file_exists($file)) echo "file exists";  //file exists
   $dir = "/usr/";
   if (file_exists($dir)) echo "directory exists"; //directory exists
?>

To check a web file exists or not:

<?PHP
    $url="http://https://convert.idontcarewhatyouthink.net/program/php/fileexists.php";
	$headers = @get_headers($url);
	if(strpos($headers[0],'200')===false)
	{
		echo "$url not exists!\n";
	}
	else echo "$url exists\n";
?>

To get all files in a directory with certain pattern, use glob() function:

<?PHP
    $dir = "/usr/";
	$arrfiles = glob('*.txt');
	var_dump($arrfiles);
?>

is_file() checks a file exists or not; is_dir() checks a directory exists or not. These two functions are faster than file_exists(), especially when the file path has multiple levels.
   bool is_file(str file)
   bool is_dir(str dir)

<?PHP
   $file = "/usr/test.txt";
   if (is_file($file)) echo "file exists";  //file exists
   $dir = "/usr/";
   if (is_dir($dir)) echo "directory exists"; //directory exists
?>

The following code compares two directories, and retrieve all files that exist in one directory but not in another.

<?PHP
	function diff2dir($olddir, $newdir)
	{
	     $files = scandir($olddir);
		 $newfiles = scandir($newdir);
		 
		 $arr = array();
		 foreach($files as $file)
		 {
				$targfile = $newdir . $file;
				if (!file_exists($targfile))
				    $arr[] = $file;
         }	
		 return $arr;
	}	
?>