PHP Programming Cookbook PDF

PHP Programming Cookbook 1 / 63 Chapter 1 PHP Tutorial for Beginners PHP (recursive acronym for PHP: Hypertext Preprocessor) is a widely-used open source general-purpose scripting language that is es...

PHP Programming Cookbook 1 / 63 Chapter 1 PHP Tutorial for Beginners PHP (recursive acronym for PHP: Hypertext Preprocessor) is a widely-used open source general-purpose scripting language that is especially suited for web development and can be embedded into HTML. It allows web developers to create dynamic content that interacts with databases. PHP is basically used for developing web based software applications. PHP is mainly focused on server-side scripting, so you can do anything any other CGI program can do, such as collect form data, generate dynamic page content, or send and receive cookies. Code is executed in servers, that is why you’ll have to install a sever-like environment enabled by programs like XAMPP which is an Apache distribution. 1.1 Introduction Back in 1994, Rasmus Lerdorf unleashed the very first version of PHP. However, now the reference implementation is now produced by The PHP Group. The term PHP originally stood for Personal Home Page but now it stands for the recursive acronym: Hypertext Preprocessor. PHP 4 and PHP 5 are distributed under the PHP Licence v3.01, which is an Open Source licence certified by the Open Source Initiative. 1.1.1 Where is PHP used? Three are the main areas where PHP scripts are used: Server-side scripting This is the most used and main target for PHP. You need three things to make this work the way you need it. The PHP parser (CGI or server module), a web server and a web browser. You need to run the web server where. You can access the PHP program output with a web browser, viewing the PHP page through the server. All these can run on your home machine if you are just experimenting with PHP programming. Command line scripting You can make a PHP script to run it without any server or browser. You only need the PHP parser to use it this way. This type of usage is ideal for scripts regularly executed using cron (on Linux) or Task Scheduler (on Windows). These scripts can also be used for simple text processing tasks. Writing desktop applications PHP may not the very best language to create a desktop application with a graphical user interface, but if you know PHP very well, and would like to use some advanced PHP features in your client-side applications you can also use PHP-GTK to write such programs. You also have the ability to write cross-platform applications this way. In this article, we’ll have a detailed look at the server-side scripting using PHP. PHP Programming Cookbook 2 / 63 1.1.2 Why PHP? There stand convincing arguments for all those who wonder why PHP is so popular today: Compatible with almost all servers used nowadays A web server is an information technology that processes requests via HTTP, the basic network protocol used to distribute information on the World Wide Web. There exist many types of web servers that servers use. Some of the most important and well-known are: Apache HTTP Server, IIS (Internet Information Services), lighttpd, Sun Java System Web Server etc. As a matter of fact, PHP is compatible with all these web servers and many more. PHP will run on most platforms Unlike some technologies that require a specific operating system or are built specifically for that, PHP is engineered to run on various platforms like Windows, Mac OSX, Linux, Unix etc) PHP supports such a wide range of databases An important reason why PHP is so used today is also related to the various databases it supports (is compatible with). Some of these databases are: DB++, dBase, Ingres, Mongo, MaxDB, MongoDB, mSQL, Mssql, MySQL, OCI8, PostgreSQL, SQLite, SQLite3 and so on. PHP is free to download and open source Anyone can start using PHP right now by downloading it from php.net. Millions of people are using PHP to create dynamic content and database-related applications that make for outstanding web systems. PHP is also open source, which means the original source code is made freely available and may be redistributed and modified. Easy to learn & large community PHP is a simple language to learn step by step. This makes it easier for people to get engaged in exploring it. It also has such a huge community online that is constantly willing to help you whenever you’re stuck (which actually happens quite a lot). The graphic below shows a basic workflow of dynamic content being passed to and from the client using PHP: PHP Programming Cookbook 3 / 63 Figure 1.1: PHP Dynamic Content Interaction 1.2 XAMPP Setup XAMPP is a free and open source cross-platform web server solution developed by Apache Friends, consisting mainly of the Apache HTTP Server, MariaDB database, and interpreters for scripts written in the PHP and Perl programming languages. In order to make your PHP code execute locally, first install XAMPP. Download XAMPP Install the program (check the technologies you want during installation) Open XAMPP and click on "Start" on Apache and MySQL (when working with databases) PHP Programming Cookbook 4 / 63 Figure 1.2: XAMPP window after a successful installation with Apache and MySQL enabled Place your web project inside the htdocs directory. In the common case, if you installed XAMPP directly inside the C: drive of your PC, the path to this folder would be: C:xampphtdocs Figure 1.3: XAMPP Directory for Web Projects To test the services are up and running you can just enter localhost in your address bar and expect the welcoming page. PHP Programming Cookbook 5 / 63 1.3 PHP Language Basics The aim of this section is to introduce the general syntax you should expect in PHP. 1.3.1 Escaping to PHP There are four ways the PHP parser engine can differentiate PHP code in a webpage: Canonical PHP Tags This is the most popular and effective PHP tag style and looks like this: Short-open Tags These are the shortest option, but they might need a bit of configuration, and you might either choose the --enable-short- tags configuration option when building PHP, or set the short_open_tag setting in your php.ini file. ASP-like Tags In order to use ASP-like tags, you’ll need to set the configuration option in the php.ini file: HTML script Tags You can define a new script with an attribute language like so:... 1.3.2 Commenting PHP Just like other languages, there are several ways to comment PHP code. Let’s have a look at the most useful ones: Use # to write single-line comments Use // to also write single-line comments Use to write multi-line comments PHP Programming Cookbook 6 / 63 1.3.3 Hello World The very basic example of outputting a text in PHP would be: The result of the above statements would be the same: "Hello World". But why are there three different ways to output? print returns a value. It always returns 1. echo can take a comma delimited list of arguments to output. printf is a direct analog of C’s printf(). 1.3.4 Variables in PHP Any type of variable in PHP starts with a leading dollar sign ($) and is assigned a variable type using the = (equals) sign. The value of a variable is the value of its most recent assignment. In PHP, variables do not need to be declared before assignment. The main data types used to construct variables are: Integers - whole numbers like 23, 1254, 964 etc Doubles - floating-point numbers like 46.2, 733.21 etc Booleans - only two possible values, true or false Strings - set of characters, like Web Code Geeks Arrays - named and indexed collections of other values Objects - instances of predefined classes The following snippet shows all of these data types declared as variables: PHP Programming Cookbook 7 / 63 1.3.5 Conditional Statements in PHP Conditional statements are used to execute different code based on different conditions. The If statement The if statement executes a piece of code if a condition is true. The syntax is: if (condition) { // code to be executed in case the condition is true } A practical example would be: Because the condition is true, the result would be: You are a teenager The If... Else statement The If... Else statement executed a piece of code if a condition is true and another piece of code if the condition is false. The syntax is: if (condition) { // code to be executed in case the condition is true } else { // code to be executed in case the condition is false } An example of an If... Else statement would be: Because the condition is false, the result in this case would be: You are an adult The If... Elseif... Else statement This kind of statement is used to define what should be executed in the case when two or more conditions are present. The syntax of this case would be: if (condition1) { // code to be executed in case condition1 is true } PHP Programming Cookbook 8 / 63 elseif (condition2) { // code to be executed in case condition2 is true } else { // code to be executed in case all conditions are false } Again, a simple example to demonstrate this: The result, as you might expect, would be: You are a kid 1.3.6 Loops in PHP In PHP, just like any other programming language, loops are used to execute the same code block for a specified number of times. Except for the common loop types (for, while, do... while), PHP also support foreach loops, which is not only specific to PHP. Languages like Javascript and C# already use foreach loops. Let’s have a closer look at how each of the loop types works. The for loop The for loop is used when the programmer knows in advance how many times the block of code should be executed. This is the most common type of loop encountered in almost every programming language. for (initialization; condition; step){ // executable code } An example where we use the for loop would be: for ($i=0; $i < 5; $i++) { echo "This is loop number $i"; } The result of this code snippet would be: This is loop number 0 This is loop number 1 This is loop number 2 This is loop number 3 This is loop number 4 The while loop The while loop is used when we want to execute a block of code as long as a test expression continues to be true. while (condition){ // executable code } PHP Programming Cookbook 9 / 63 An example where we use the while loop would be: $i=0; // initialization while ($i < 5) { echo "This is loop number $i"; $i++; // step } The result of this code snippet would be just the same as before: This is loop number 0 This is loop number 1 This is loop number 2 This is loop number 3 This is loop number 4 To have a clearer idea of the flow of these two loops, look at the graphic below: Figure 1.4: PHP for and while Loops The do... while loop PHP Programming Cookbook 10 / 63 The do...while loop is used when we want to execute a block of code at least once and then as long as a test expression is true. do { // executable code } while (condition); An example where we use the do... while loop would be: $i = 0; // initialization do { $i++; // step echo "This is loop number $i"; } while ($i < 5); // condition This time the first loop number would be 1, because the first echo was executed only after variable incrementation: This is loop number 1 This is loop number 2 This is loop number 3 This is loop number 4 This is loop number 5 The foreach loop The foreach loop is used to loop through arrays, using a logic where for each pass, the array element is considered a value and the array pointer is advanced by one, so that the next element can be processed. foreach (array as value) { // executable code } An example where we use the foreach loop would be: $var = array(’a’,’b’,’c’,’d’,’e’); // array declaration foreach ($var as $key) { echo "Element is $key"; } This time the first loop number would be 1, because the first echo was executed only after variable incrementation: Element is a Element is b Element is c Element is d Element is e 1.4 PHP Arrays Arrays are used to store multiple values in a single variable. A simple example of an array in PHP would be: PHP Programming Cookbook 11 / 63 Array elements are accessed like this: $arrayName[positionIndex]. For the above example we could access "PHP" this way: $languages. Position index is 1 because in programming languages the first element is always element 0. So, PHP would be 1 in this case. There are three types of arrays in PHP: Indexed Arrays We can create these kind of arrays in two ways shown below: An example where we print values from the array is: // RESULT My friends are Fabio, Klevi and John Looping through an indexed array is done like so: This would just print the values of the array. Associative Arrays Associative arrays are arrays which use named keys that you assign. Again, there are two ways we can create them: An example where we print values from the array is: PHP Programming Cookbook 12 / 63 // RESULT Fabio’s age is 20 years old. Looping through an associative array is done like so: Key = Fabio, Value = 20 Key = Klevi, Value = 16 Key = John, Value = 43 Multidimensional Arrays This is a rather advanced PHP stuff, but for the sake of this tutorial, just understand what a multidimensional array is. Basically, it is an arrays the elements of which are other arrays. For example, a three-dimensional array is an array of arrays of arrays. An example of this kind of array would be: 1.5 PHP Functions Functions are a type of procedure or routine that gets executed whenever some other code block calls it. PHP has over 1000 built-in functions. These functions help developers avoid redundant work and focus more on the logic rather than routine things. Apart from its own functions, PHP also let’s you create your own functions. The basic syntax of a function that we create is: Every function needs a name, optionally has one or more arguments and most importantly, defines some kind of procedure to be followed within the body, that is, code to be executed. Let’s see some basic functions: This function would just print the message we wrote: Hello Chloe! Another example would be a function with arguments: This time we’d have: Hi there, Fabio Hi there, Michael More than one argument can be used whenever needed: The result would include the printed message together with the arguments: This person is Fabio from Tirana. His/Her job is Web Dev. This person is Michael from Athens. His/Her job is Graphic Designer. This person is Xena from London. His/Her job is Tailor. In PHP, just like in many other languages, we can tell functions to return a value upon executing the code. Such example would be: The result would be: PHP Programming Cookbook 14 / 63 The difference of the given numbers is: 5 PHP also provides quite useful functions for developers to use. One of them is the mail() function. Have a detailed look of how you can use this function to send e-mails in this article 1.6 Connecting to a Database There are four ways you can generally consider when you want to connect to a previously created database. Below, we’ll explain how you can use each of them beginning with the easiest one. 1.6.1 Connecting to MySQL Databases The syntax for connecting to a MySQL database would be: Considering your entered information is correct, you’d be successfully connected to the right database and ready to start writing and test your queries. Else, the respective error message would appear as defined by the die function. However, do keep in mind that the mysql extension is deprecated and will be removed in the future, so the next methods can be used for databases. 1.6.2 Connecting to MySQLi Databases (Procedurial) The MySQLi stands for MySQL improved. The syntax for connecting to a database using MySQLi extension is: This is a good way to start, because it is easy to understand and gets the job done. However, object oriented logic that we’ll see below is what everyone should be getting into because of the other components of programming being used in this paradigm and also because it is kind of more structured way of doing things. PHP Programming Cookbook 15 / 63 1.6.3 Connecting to MySQLi databases (Object-Oriented) Although the functionality is basically the same, this is another way, the object-oriented way of connecting to a database using the MySQLi extension. $username = "your_name"; $password = "your_password"; $hostname = "localhost"; // create connection $dbConnect = new mysqli($hostname, $username, $password); // check connection if ($dbConnect->connect_error) { die("Connection failed: ". $dbConnect->connect_error); } echo "Connected successfully"; // select a specific database $mysqli->select_db("dbName"); Even in this case, you can check to see if the database was successfully selected, but it is a matter of choice. Object-Oriented MySQLi is not a different MySQLi as far as code functionality is concerned, but rather a different way/logic of writing it. 1.6.4 Connecting to PDO Databases PDO stands for PHP Data Objects and is a consistent way to access databases, which promises much easier portable code. PDO is more like a data access layer which uses a unified API rather than an abstraction layer. The syntax for connecting to a database using PDO is: $username = "your_name"; $password = "your_password"; $hostname = "localhost"; // try to create connection try { $dbConnect = new PDO("mysql:host=$hostname;dbname=myDB", $username, $password); // set the PDO error mode to exception $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); echo "Connected successfully"; } // show an error if the connection was unsuccessful catch(PDOException $e) { echo "Connection failed: ". $e->getMessage(); } PDO is widely used today for a bunch of advantages it offers. Among them, we can mention that PDO allows for prepared statements and rollback functionality which makes it really consistent, it throws catchable exceptions which means better error handling and uses blind parameters in statements which increases security. 1.7 PHP Form Handling In HTML, forms are used to collect user input/information. But, as far as HTML goes, it just provides the graphical interface and the ability to write on the input fields. However, the aim we collect user information is because we need to process this information. That usually means saving the inputs to a database so that they can be accessed later for several purposes. In this section, we will not send information to the database, as that requires an active database that is already set up and includes knowledge form SQL language, but we can retrieve information that the user has given us. That being said, it is important to PHP Programming Cookbook 16 / 63 have a way to get information, becuase what you use it for and where you want to show/save it depends. Let’s have a look at the HTML form below: Male Female This form is just a regular one, and includes inputs for name, e-mail, age and gender. This information will be subject of a print when the Submit button is clicked. That just proves that we got the information from the user. For now, let’s see what we got and fill the form: Figure 1.5: HTML form we just created Next, we check each input to make sure the user has written/chosen something, and the input is not empty. We do this using two well-known functions in PHP, the isset() and empty(). After making sure we have this right, we can also validate fields. In this case, only the name input may need some sort of validation to make sure one simply doesn’t write numbers in there, while other inputs are more or less validated from HTML5, in the case of email and age. Validation is a must for all fields when considering real web projects. We recommend having a closer look to our article on PHP Form Validation Example If the fields have been set, information about each field will be printed. After clicking the "Submit" button, the result we’d have is: Name: Alex Brown E-Mail: [email protected] Age: 28 Gender: Male As you may have noticed by now, we used this $_POST["name"] to get information the user posted. What about implementing a login form in PHP? Have a look at our Login Form in PHP Example. 1.8 PHP Include & Require Statements PHP code can get cluttered, which means that if you want to later change something, it becomes a hard task to do. Include and require statements are two almost identical statements that help in an important aspect of coding, the organization of code, and making it more readable and flexible. The include/require statement copies all text, code or any other markup from one existing file to the file using the statement. In a simple viewpoint, do consider these statements like this: PHP Programming Cookbook 18 / 63 Figure 1.6: PHP Include Statement The include and require statements are the same, except upon failure of code execution where: require will produce a fatal error (E_COMPILE_ERROR) and stop the script from executing include will only produce a warning (E_WARNING) and the script will continue The syntax of these two statements is as follows: Let’s now see a real-world example where we use a header and footer using include and require into our main file: header.php Home Profile About Contact PHP Programming Cookbook 19 / 63 // styling to make the menu look right ul, li { list-style-type: none; display: inline-block; margin-right: 1em; padding: 0; } footer.php All Rights Reserved. Do not reproduce this page. In our main file, we’ll use require for the header.php and include for the footer.php file: index.php Main Content Goes Here The result, as you might have an idea by now, would be the whole code being shown as one: Figure 1.7: The result of using include and require in our main file 1.9 Object Oriented Concepts Object oriented programming is a programming language model in the center of which are objects. Let’s see some of the core concepts of classes and objects before we see actual examples of them: Class A class is a predefined (by a programmer) data type, part of which are local data like variables, functions etc. Object An object is an instance of a class. Objects can only be created after a class has been define. A programmer can create several objects. PHP Programming Cookbook 20 / 63 Constructor A constructor refers to the concept where all data and member functions are encapsulated to form an object. A destructor, on the other hand, is called automatically whenever an object is deleted or goes out of scope. 1.9.1 PHP Classes Let’s now define a new clas in PHP. But that is just how the syntax looks like. Below, we give an example of a real-world class, for example class Vehicle: The result of this code would be: Vehicle brand is: Audi Vehicle speed is: 120 As you can see, the speed is changed to the latest value set by us. 1.9.2 PHP Constructor Function PHP provides a special function called __construct() to define a constructor, which can take as many arguments as we want. Constructors are called automatically whenever an object is created. Let’s see how we adopt this into our previously created class. The following code snipper is found inside the class: PHP Programming Cookbook 21 / 63 The result now is: Vehicle brand is: Toyota Vehicle speed is: 130 Vehicle brand is: Ferrari Vehicle speed is: 450 PHP contains such object oriented rules just like other languages like Java, and as you go on learning it in further details, you’ll see that you can do more with those variables we declare inside a class, you can set scope to them so that they can only be accessed within a class, a function etc. Also, other concepts like methods overriding is normal when using PHP, as declaring the same method for the second time but with different arguments or code logic, will make the program execute only the latest method it finds in the file. 1.10 Conclusion PHP is the fundamental back-end development technology regarding usage and learning curve. It combines such features that make for interactive web pages that people love to use everyday. In this article, we detailed the basic concepts to give you a clear idea of how it can be used in different aspects and information that you might as well relate to other programming languages like loops and conditionals, as most languages recognize these concepts and make use of them. In the early days, everyone used PHP in a rather procedurial style, as a way to get things done when you don’t know a lot, but as you learn more and more, you’ll love working with object-oriented PHP which will make your programming life way much easier and sustainable in big projects. It is important to understand that there are many ways pages could be made dynamic in PHP, and different developers might as well have a totally distinct code that does the same task, that is some kind of flexibility that you get to decide how you are going to implement certain functions (randomly called procedures in PHP). So, just give it a try, you have nothing to lose. 1.11 Download the source code Download You can download the full source code of this example here: PHP-Tutorial-Samples PHP Programming Cookbook 22 / 63 Chapter 2 Upload Script Example In this example, we are going to see how to make file uploads with PHP, that is, how to upload a file from the client side, to the server side. The process itself is pretty simple, but several checks have to be done to ensure that the file upload is made safely, i.e., to neutralise any hypothetical malicious misuse; and to be able to detect every possible error to act accordingly, so, this is something that must be done carefully. For this tutorial, we will use: Ubuntu (14.04) as Operating System. Apache HTTP server (2.4.7). PHP (5.5.9). 2.1 Preparing the environment 2.1.1 Installation Below, are shown the commands to install Apache and PHP: sudo apt-get update sudo apt-get install apache2 php5 libapache2-mod-php5 sudo service apache2 restart 2.1.2 PHP configuration Is necessary to configure PHP to allow file uploads. With your favourite editor, open the php.ini file: sudo vi /etc/php5/apache2/php.ini And check that the file_uploads directive value is set to On: file_uploads = On If you want, you can change the upload_max_filesize directive, to change the maximum size allowed for upload. Don’t forget to restart Apache after doing any change. Note: if you want to use Windows, installing XAMPP is the fastest and easiest way to install a complete web server that meets the prerequisites. PHP Programming Cookbook 23 / 63 2.2 Upload form First, we need to create a form, where the file will be attached. It should be similar to this: upload_form.html Upload form Select a file to upload: There are several things to take into account: Form action must point to the PHP file that will perform the upload (this is quite obvious). Submission method must be POST. Form enctype attribute must be specified, with multipart/form-data value. This is not to make the form encode the characters. 2.2.1 Accepting only certain type of files It is possible to restrict the uploading files to only expected file types. This can be made in several ways: By file extension. For example, if we are expecting a document, we can restrict the extensions to.pdf and.doc. By file type. We can directly say that we are expecting an image, an audio or/and a video. By media type, specifying the MIME type. An example could be text/plain, if we are expecting plain files. All of these can be combinated, so we could say, for example, that we are expecting a document file, and it can be accepted in pdf, doc, docx and odt and format. Applying this last example to the form above (line 11), the result would be the following: upload_form.html As you can see, the conditions are sepparated by comma. Note: keep always in mind that client-side validation is never enough. Every validation we do in the client-side, it should be done also in the server - remember that here is the person in the client-side who has the control, not you! PHP Programming Cookbook 24 / 63 2.3 PHP upload script Once the form is submitted, is time for the server to handle the upload. The following script will do the job: upload.php To use session in php we call the session_start() function before anything else is output to the browser. All session variable values are stored in the global $_SESSION associative array. Assigning a session variable is as simple as writing $_SESSION[’num’]=1 and we can read from it the same way we would read from a normal variable. We use the $_SESSI ON[’num’] variable as a counter to store the number of times the script has received a record. action.php if($_SESSION[’num’]==1){ $_SESSION[’num’]++; $_SESSION[’first’]=$_POST[’first’]; $_SESSION[’last’]= $_POST[’last’]; $_SESSION[’subject’]=$_POST[’subject’]; $_SESSION[’score’]=$_POST[’score’]; include("index.html"); } else if($_SESSION[’num’]==2){ $_SESSION[’num’]++; $_SESSION[’first1’]=$_POST[’first’]; $_SESSION[’last1’]= $_POST[’last’]; $_SESSION[’subject1’]=$_POST[’subject’]; $_SESSION[’score1’]=$_POST[’score’]; include("index.html"); } else if($_SESSION[’num’]>=3){ $_SESSION[’num’]=1; $_SESSION[’first2’]=$_POST[’first’]; $_SESSION[’last2’]= $_POST[’last’]; $_SESSION[’subject2’]=$_POST[’subject’]; PHP Programming Cookbook 62 / 63 $_SESSION[’score2’]=$_POST[’score’]; ?> Dynamic php and html table testing html, body{ width:100%; height:100%; margin:0%; font-family:"helvetica","verdana","calibri", "san serif"; overflow:hidden; padding:0%; border:0%; } table{ width:50%; border:2px solid #343434; margin-left:auto; margin-right:auto; } td{ text-align:center; width:25%; border:2px solid #343434; } #he{ height:10%; background-color:#343434; margin-bottom:2%; } Student Result Score FirstnameLastnameSubjectScore We check how many times our script has received a record, if it’s not up to three we increment our counter variable, store each record received in our session array and display the form to the teacher(we do this by calling the include("index.html") function). After three records has been submitted we reset the counter variable and output an html table containing each student record to the browser. It is considered good practice to clean up after using session. we call php session_unset() to delete all session data and session_destroy() to the destroy the session. 8.1.3 Html Tables Let’s start by explaining each tag used in our example The tag: it is used to define/create a table in html The tag: it is used to define an header for a table. The tag: it is used in conjunction with the and tag to describe a table. It always comes after the tag and before the tag The tag: it is used to define a row in an html table The tag: This tag defines a table header. The tag: This tag defines a cell in an html table 8.1.4 Other table tags worthy of mention tag : This is an optional tag, it gives the title of the table. It is always the first descendant of the tag. : This tag defines a set of rows summarizing the columns of the table. 8.2 Summary In this example we have learnt about dynamic php and html tables(what they mean and how to use them). we also discussed about html forms and php sessions(how to create and destroy them). 8.3 Download the source code Download You can download the full source code of this example here: Phphtmltableexample