File I/O – PHP Best Practices

Outline

• Files• Files in PHP• Traversing Directories• Serialization• PHP Best Practices

Files• Files are data records on the hard disk. We use them

to save persistent data.

• We are responsible for the format in which we will write the data to the file.

Files in PHP• string file_get_contents ($file)

• This function is used to get file contents from local file system, or from an external URL.

• file_put_contents($file, $data)

• Saves a string to a file.

Files in PHP• array file ( string $filename ):

• Takes a file path and returns an array containing each line from that file content.

• bool file_exists($file) :

• Checks whether the passed file exists.

Files in PHP• int filesize($file) :

• Returns the size of the specified file in bytes.

Traversing Directories• Traversing Directories :

• Directory traversing fits the recursive model. It can be done using recursion.

• Using the functions opendir(), is_dir(), closedir(), we will be implementing a solution to traverse a certain directory and display all the directories and files inside it.

Traversing Directoriesfunction traverse($dir) { echo "Directory: $dir <br>"; if( !( $dp = opendir($dir) ) ) return; while((false !== $file = readdir($dp))){ if($file != '.' && $file !='..'){ if(is_dir("$dir/$file") ){ traverse("$dir/$file"); } else{ echo "File: $dir/$file<br>"; } } } closedir($dp); }traverse('/var/www');

Serialization• Serlialize($item):

• Use this function to convert any type to a string to save it to a file ( or for any other use ).

<?php$var = array( ‘1’ => ‘xxx’, ‘2’ => ‘yyy’ );echo serialize($var); // a:2:

{i:1;s:3:"xxx";i:2;s:3:"yyy";}

?>

Serialization• mixed unserlialize($item):

• It does the opposite of serialize(), it converts the serialized object back to its original value.

<?php$var = array( ‘1’ => ‘xxx’, ‘2’ => ‘yyy’ );echo unserialize( serialize($var) );

?>

PHP Best Practices

1. Always escape output. Use htmlspecialchars().

2. Always filter/ validate user input.

3. Don't copy variables for no reason.$description = strip_tags($_POST['description']);

$description = ‘something’ . $description;

echo $description;

4. Favor built-in functions over custom functions.

PHP Best Practices

5. Use regular expressions only when necessary, use string functions if they achieve what’s required instead.

6. Remember that disk I/O is the slowest operation you can do.

7. Use opcode cache to cache the PHP intermediate code ( APC cache ).

8. Know the difference between single and double quotes.

9. Use echo instead of print.

Questions?

We hope you enjoyed the course and it was of a good value to you.

Please keep in touch,Ahmed KamalFacebook : /ahmed.kamalSkype: nc_a.kamalMobile : 0104740817

Ahmed SwilamFacebook : /ahmed.swilamSkype: nc_a.swilamMobile : 0108247940

Best wishes