.php

//Create a File
$my_file = 'file.txt';
$handle = fopen($my_file, 'w') or die('Cannot open file:  '.$my_file); //implicitly creates file

//Open a File
$my_file = 'file.txt';
$handle = fopen($my_file, 'w') or die('Cannot open file:  '.$my_file); //open file for writing ('w','r','a')...

//Read a File
$my_file = 'file.txt';
$handle = fopen($my_file, 'r');
$data = fread($handle,filesize($my_file));

//Write to a File
$my_file = 'file.txt';
$handle = fopen($my_file, 'w') or die('Cannot open file:  '.$my_file);
$data = 'This is the data';
fwrite($handle, $data);

//Append to a File
$my_file = 'file.txt';
$handle = fopen($my_file, 'a') or die('Cannot open file:  '.$my_file);
$data = 'New data line 1';
fwrite($handle, $data);
$new_data = "\n".'New data line 2';
fwrite($handle, $new_data);

//Close a File
$my_file = 'file.txt';
$handle = fopen($my_file, 'w') or die('Cannot open file:  '.$my_file);
//write some data here
fclose($handle);

//Delete a File
$my_file = 'file.txt';
unlink($my_file);

//Create a folder if it is not exist
if (!file_exists('path/to/directory')) {
    mkdir('path/to/directory', 0777, true);
}