Monday, April 21, 2014

PHP - Coding Standard

php coding standards

Every company follows a different coding standard based on their best practices. Coding standard is required because there may be many developers working on different modules so if they will start inventing their own standards then source will become very un-manageable and it will become difficult to maintain that source code in future.
Here are several reasons why to use coding specifications:
  • Your peer programmers have to understand the code you produce. A coding standard acts as the blueprint for all the team to decipher the code.
  • Simplicity and clarity achieved by consistent coding saves you from common mistakes.
  • If you revise your code after some time then it becomes easy to understand that code.
  • Its industry standard to follow a particular standard to being more quality in software.

PHP File Uploading

php file upload

A PHP script can be used with a HTML form to allow users to upload files to the server. Initially files are uploaded into a temporary directory and then relocated to a target destination by a PHP script.
Information in the phpinfo.php page describes the temporary directory that is used for file uploads as upload_tmp_dir and the maximum permitted size of files that can be uploaded is stated as upload_max_filesize. These parameters are set into PHP configuration file php.ini
The process of uploading a file follows these steps
  • The user opens the page containing a HTML form featuring a text files, a browse button and a submit button.
  • The user clicks the browse button and selects a file to upload from the local PC.
  • The full path to the selected file appears in the text filed then the user clicks the submit button.
  • The selected file is sent to the temporary directory on the server.
  • The PHP script that was specified as the form handler in the form's action attribute checks that the file has arrived and then copies the file into an intended directory.
  • The PHP script confirms the success to the user.
As usual when writing files it is necessary for both temporary and final locations to have permissions set that enable file writing. If either is set to be read-only then process will fail.
An uploaded file could be a text file or image file or any document.

PHP - Sending Emails

php mail

PHP must be configured correctly in the php.ini file with the details of how your system sends email. Open php.ini file available in /etc/ directory and find the section headed [mail function].
Windows users should ensure that two directives are supplied. The first is called SMTP that defines your email server address. The second is called sendmail_from which defines your own email address.
The configuration for Windows should look something like this:

PHP Sessions

php session

An alternative way to make data accessible across the various pages of an entire website is to use a PHP Session.
A session creates a file in a temporary directory on the server where registered session variables and their values are stored. This data will be available to all pages on the site during that visit.
The location of the temporary file is determined by a setting in the php.ini file calledsession.save_path. Bore using any session variable make sure you have setup this path.
When a session is started following things happen:
  • PHP first creates a unique identifier for that particular session which is a random string of 32 hexadecimal numbers such as 3c7foj34c3jj973hjkop2fc937e3443.
  • A cookie called PHPSESSID is automatically sent to the user's computer to store unique session identification string.
  • A file is automatically created on the server in the designated temporary directory and bears the name of the unique identifier prefixed by sess_ ie sess_3c7foj34c3jj973hjkop2fc937e3443.

PHP Cookies

php cookies

Cookies are text files stored on the client computer and they are kept of use tracking purpose. PHP transparently supports HTTP cookies.
There are three steps involved in identifying returning users:
  • Server script sends a set of cookies to the browser. For example name, age, or identification number etc.
  • Browser stores this information on local machine for future use.
  • When next time browser sends any request to web server then it sends those cookies information to the server and server uses that information to identify the user.
This chapter will teach you how to set cookies, how to access them and how to delete them.

PHP Functions

php functions

PHP functions are similar to other programming languages. A function is a piece of code which takes one more input in the form of parameter and does some processing and returns a value.
You already have seen many functions like fopen() and fread() etc. They are built-in functions but PHP gives you option to create your own functions as well.
There are two parts which should be clear to you:
  • Creating a PHP Function
  • Calling a PHP Function
In fact you hardly need to create your own PHP function because there are already more than 1000 of built-in library functions created for different area and you just need to call them according to your requirement.
Please refer to PHP Function Reference for a complete set of useful functions.

PHP Files & I/O

php file handling

This chapter will explain following functions related to files:
  • Opening a file
  • Reading a file
  • Writing a file
  • Closing a file

Opening and Closing Files

The PHP fopen() function is used to open a file. It requires two arguments stating first the file name and then mode in which to operate.
Files modes can be specified as one of the six options in this table.