PHP Loops

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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.

  1. To start our project let’s create a new folder named Loops in the htdocs folder in the xampp folder in C drive.
  2. Open a new notepad++ file and save it as index.php in the newly created folder named Loops in htdocs folder.
  3. Open this project in browser by just writing localhost/Loops in the address bar. You will see the following output:
  4. initial_output
    fig 1

  5. Let’s start with PHP loops.
  6. Loops in PHP have the same syntax as we used in javascript.

    1. FOR LOOP
      • Syntax for a for loop is shown below:

      • Let us try one example. Write the following code in index.php document:
      • Here, we are dealing with PHP, so have included the code within 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:
      • for_loop_output
        fig 2

    2. WHILE LOOP
      • Syntax for while loop is show below:
      • Let us try the same example shown above using while loop. Write the following code in index.php document:
      • 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:
      • while_loop_output
        fig 3

    3. FOREACH LOOP
      • Syntax for a foreach loop is shown below:
      • Let us try it with an example. Write the following code in index.php document:
      • 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:
      • foreach_loop_output
        fig 4

  7. 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.
  8. 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:
    • Your page will look like this:
    • initial_output
      fig 5

  9. 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 :
    • 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.
  10. 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 tag:
    • This statement will decode the JSON data and store it in the variable $json.
  11. Now we have the decoded data with us. So to represent it using php and html write the following code in the tags.
    • 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:

    movies_info
    fig 6

  12. 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:
    • 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:
    • styled_output
      fig 7

Thus we finished with our PHP loops and a task of grabbing JSON file data and displaying it using PHP in this PHP Loops tutorial.

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