#php loops

PHP Loops

In this section we are going to learn about different loops in PHP and use a loop in displaying the information from a JSON file. I mean we are going to create a project in which we are going to get the information stored in “movies.json” file created in section 4 and then loop through the JSON file using PHP. So let’s learn about loops and how to extract data from a json file using PHP in this PHP Loops tutorial.

To start our project let’s create a new folder named Loops in the htdocs folder in the xampp folder in C drive.

Open a new notepad++ file and save it as index.php in the newly created folder named Loops in htdocs folder.

Open this project in browser by just writing localhost/Loops in the address bar. You will see the following output:

fig 1

Let’s start with PHP loops.

Loops in PHP have the same syntax as we used in javascript.

FOR LOOP

Syntax for a for loop is shown below:

for(initialization;condition;increment/decrement)   Statement(s);

Let us try one example. Write the following code in index.php document:

<?php for($i=0;$i<=10;$i++)   echo 'Number '.$i.'<br/>'; ?>

Here, we are dealing with PHP, so have included the code within

<?php?>

tag.

For loop has a variable $i initialized to 0 having condition $i<=10 and incrementing $i with every iteration.

The statement echo displays a string “Number ” with the value of $i variable concatenated with it using a period(.) in every iteration till the condition is satisfied.

Brake tag is used for a line brake.

The process of displaying will continue till the condition is true. Once the condition becomes false, the loop will terminate.

Now just reload the page and see the output as shown below:

fig 2

WHILE LOOP

Syntax for while loop is show below:

Variable initialization; while(condition)   Statement(s);   Increment/decrement;

Let us try the same example shown above using while loop. Write the following code in index.php document:

<?php $i=0; while($i<=10)   echo 'Number '.$i.'<br/>';   $i++; ?>

Here, we have initialized $i variable to zero(0) initially.

Next we have given the condition $i<=10 in the while statement.

The statement echo inside the while block will display the string “Number ” with the value of $i as it changes in every iteration.

The statement $i++; is used to increment the value of $i after displaying it. But remember if you forget to increment/decrement its value, the loop will become an infinite loop. This will happen because the value of $i will remain constant and it will always satisfy the condition and will always return true.

Now reload the browser and see the output, it is shown below:

fig 3

FOREACH LOOP

Syntax for a foreach loop is shown below:

foreach(Variable_pointing_to_array as variable_traversing_through_array)   Statement(s);

Let us try it with an example. Write the following code in index.php document:

<?php $people=array('Robbin','Michael','Jeorge','Kevin'); foreach($people as $person)   echo $person.'<br/>'; ?>

Here, we have declared an array named $people. We want to just display the names in the array using foreach loop.

The foreach loop contains array name i.e. $people, as keyword and a variable $person for traversing the array $people.

The variable $person fetches one value from the array and then auto-increments itself to point to the next value in the array with every iteration.

We have displayed the array contents using echo statement.

Now reload the browser and see the output. The output is shown below:

fig 4

Now we have learned the loops, so let us turn to the next part of our project i.e. looping through a JSON file using PHP.

For this copy the movies.json file created in some of the previous chapters of section 4 “XML,JSON and AJAX” and paste in our Loops folder created for this project in htdocs file.

Since we want to display data in a systematic way we need to use html in this project.

So write the following HTML code in index.php document. You can comment all the loop examples taken above.

Comments in PHP are :

// — single line comment

/* —-*/ — multiline comment

HTML code is as follows:

<!DOCTYPE html> <html> <head> <title>My Movies</title> </head> <body> </body> </html>

Your page will look like this:

fig 5

Now to show the information on the webpage we need to grab the contents of the movies.json file. So write the following code above the statement

<!DOCTYPE html>

:

<?php $jsondata=file_get_contents("movies.json"); ?>

Here, we have not given the full path of movies.json file because our index.php file and movies.json file are in the same folder.

Due to the above code we will get all the data from the movies.json file and it will be stored in the variable $jsondata.

If we are working with a website and we want data from a URL, we can use the URL in place of the file name.

We got the data from the JSON file and stored it in the variable $jsondata. Next thing we want to do is decode the JSON data so that we could parse it with php. So write the following statement below the statement written in step 7 inside the

<?php?>

tag:

$json=json_decode($jsondata,true);

This statement will decode the JSON data and store it in the variable $json.

Now we have the decoded data with us. So to represent it using php and html write the following code in the

<body>---</body>

tags.

<body> <div id="container"> <h1>My Favourite Movies</h1> <ul>     <?php          foreach($json['movies'] as $key=>$value)        echo '<h4>'.$value['title'].'</h4>';     echo '<li>Year: '.$value['year'].'</li>';     echo '<li>Genre: '.$value['genre'].'</li>';     echo '<li>Director: '.$value['director'].'</li>';        ?> </ul> </div> </body>

Here, we are representing the information in an un-ordered list.

The whole information is contained in a div tag with id “container”. It will be easy to apply styling to the information.

We have used PHP to display the decoded information stored in the variable $json.

foreach loop is used to display the contents of the array.

The title of the movie is displayed in an h4 heading tag and the details of the movie viz. year, genre and director are displayed in the li tags.

Output after writing the above code is shown below:

fig 6

Now as we have displayed all the information, we will apply some styling to it. Write the following code in the head section of the page:

<style>   h1        text-align:center;         h4        margin:0;     padding:5px;     background:#f4f4f4;         li        list-style:none;     padding-left:5px;         #container        width:600px;     margin:auto;     overflow:hidden;    </style>

Here, we have styled the h1, h4, li tags and container id.

Due to the text-align:center; style applied to the h1 tag, the heading My Favourite Movies is aligned to centre.

Next each movie title is given the margin of zero pixels, padding of 5 pixels from all sides and a gray background color; as it is in h4 tag.

Next the bullets of each list item are removed using the statement list-style:none and a padding of 5 pixels is given from left side.

Next the id container is styled with width of 600 pixels. This will club all the information within the width of 600 pixels.

A margin with value autois given to the container div so that the contents of the container div are always shown at the centre.

The styling overflow:hidden; is used to hide any overflown data.

Output of the styled webpage is shown below:

fig 7