1. Introduction

This tutorial aims to provide you with an understanding of file operations in PHP, focusing on best practices for opening, reading, writing, and closing files. By the end of this tutorial, you will be able to handle file operations more efficiently, securely, and robustly in your PHP code.

Prerequisites:
- Basic knowledge of PHP
- Familiarity with the concept of file operations

2. Step-by-Step Guide

File operations are essential in any programming language, and PHP is no exception. They allow us to store information, read from, and manipulate files. Here are some best practices.

Opening Files:
Use fopen() function to open files. Always check if the file opening was successful before proceeding.

$file = @fopen('file.txt', 'r');
if($file == false) {
  die('Error in opening file');
}

Reading Files:
fgets() or fread() can be used for reading files. Always check for the end of file using feof().

while (!feof($file)) {
  $line = fgets($file);
  // process the line
}

Writing Files:
fwrite() or file_put_contents() can be used for writing files. Always check if the writing was successful.

$written = fwrite($file, $content);
if($written == false) {
  die('Error in writing to file');
}

Closing Files:
Always close the file you have opened once you're done. Use fclose() for this.

fclose($file);

3. Code Examples

Example 1: Reading from a file

$file = @fopen('file.txt', 'r');
if($file == false) {
  die('Error in opening file');
}

while (!feof($file)) {
  $line = fgets($file);
  echo $line . "<br>";
}

fclose($file);

This code opens a file named 'file.txt' for reading ('r'), reads each line until the end of the file, and prints it. It closes the file afterwards.

Example 2: Writing to a file

$file = @fopen('file.txt', 'w');
if($file == false) {
  die('Error in opening file');
}

$content = "Hello, World!";
$written = fwrite($file, $content);
if($written == false) {
  die('Error in writing to file');
}

fclose($file);

This code opens a file named 'file.txt' for writing ('w'), writes "Hello, World!" to it, and closes the file afterwards.

4. Summary

In this tutorial, we learned about file operations in PHP, specifically how to open, read, write, and close files. We also went over some best practices like always checking if file operations were successful and always closing files after we're done.

For further learning, you could explore file handling functions in PHP's official documentation.

5. Practice Exercises

Exercise 1: Write a PHP script to read a file and count the number of lines in it.

Exercise 2: Write a PHP script to write an array of strings to a file, with each string on a new line.

Exercise 3: Write a PHP script to open a file, replace a specific word in the content, and write the result back to the file.

Tips: Use file_get_contents() and file_put_contents() for simplicity. Remember to always check if file operations are successful.