The is_dir() function in PHP allows users to check whether a file is a directory. It returns true if the file is a directory. However, the addresses provided must be RELATIVE TO THE CURRENT DIRECTORY. Suppose we have a directory structure as follows:
cwd
|-- dir1
|-- dir2
|-- dir3where cwd is the current working directory
is_dir(dir1); // returns true
is_dir(dir2); // returns false
is_dir(dir1/dir2); // returns true