How can I use the mkdir function to create a directory in PHP? Example code:

$directory = "/path/to/directory";

mkdir($directory);

How can I use the array_keys function to get an array of keys from an associative array in PHP? Example code:

How can I use the array_rand function to get a random key from an array in PHP? Example code:

How can I use a try-catch block in PHP? Example code:

How can I convert a string to uppercase in PHP? Example code:

How can I use the array_intersect function to get the common elements between two or more arrays in PHP? Example code:

How can I format a date in PHP? Example code:

How can I send an email using PHP? Example code

How can I create a multidimensional array in PHP? Example code:

How can I use the is_writable function to check if a file is writable in PHP? Example code:

How can I calculate the difference between two dates in PHP? Example code:

How can I replace a substring in a string in PHP? Example code:

How can I use the array_push function to add an element to an array in PHP? Example code:

How can I use the array_slice function to get a portion of an array in PHP? Example code:

How can I calculate the sum of an array in PHP? Example code:

How can I use the array_reverse function to reverse the order of an array in PHP? Example code:

How can I upload a file using PHP? Example code

How can I get the current date and time in PHP? Example code:

How can I delete a file in PHP? Example code:

How can I use an elseif statement in PHP? Example code:

How can I use the json_decode function to convert a JSON string to an array or object in PHP? Example code:

How can I validate a form using PHP? Example code

How can I create a class in PHP? Example code:

How can I use the file_get_contents function to read the contents of a file into a string in PHP? Example code:

How can I use the filesize function to get the size of a file in PHP? Example code:

How can I use the strrev function to reverse a string in PHP? Example code:

How can I use the array_chunk function to split an array into chunks in PHP? Example code:

How can I trim whitespace from the beginning and end of a string in PHP? Example code:

How can I use the scandir function to get a list of files and directories in a directory in PHP? Example code:

How can I use the file_put_contents function to write a string to a file in PHP? Example code:

How can I use the filemtime function to get the last modified time of a file in PHP? Example code: