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Embedding PHP code on a page

From: PHP with MySQL Essential Training

Video: Embedding PHP code on a page

Now that we have PHP installed. Were ready to start learning how to use it. We're going to start by learning how to embed PHP code in a page. Because there's some basic rules that we need to know about. We already did this in the setup chapter. We created our first file which was my_PHPinfo.PHP. And we populate with just this one little snippet of code. And you may not have completely understood what it was at the time, you may have just followed along. That's okay were now going to talk about it, and talk about how this works. Notice that there's the beginning, and ending to this line with a bit of code in the middle.

Embedding PHP code on a page

Now that we have PHP installed. Were ready to start learning how to use it. We're going to start by learning how to embed PHP code in a page. Because there's some basic rules that we need to know about. We already did this in the setup chapter. We created our first file which was my_PHPinfo.PHP. And we populate with just this one little snippet of code. And you may not have completely understood what it was at the time, you may have just followed along. That's okay were now going to talk about it, and talk about how this works. Notice that there's the beginning, and ending to this line with a bit of code in the middle.

I'll drop out the code in the middle, so you can really see the difference. This is the beginning of opening a PHP tag, and the end, closing PHP. What we're doing is essentially saying to the Apache server, hey, as you're processing this document, turn on PHP. Start reading the next little bit as being PHP code, and then when it gets to the end and it sees that question mark with the greater than, The tag is over. Now we're done with PHP. You can go back to doing your regular html rendering.

This allows us to embed PHP into the html. Remember, in the early introduction I talked about taht that's one of the features of PHP. Is that we can just embed in the html code. So we're essentially telling Apache to turn on and turn off PHP filtering as it's going through the document. And then in between, we can put whatever PHP code that we want. So if you look at somebody else's PHP code,you're going to see these open and closing tags throughout the document, as it's turned on and off. This isn't the only way that you can write these PHP tags. There's also something called Short-Open Tags.

These, I would say, are considered bad form. This is using the same tag, but omitting the letters PHP from it. There's also a form that uses the question mark followed by an equal sign which outputs the results directly. normally evaluating the PHP doesn't output results on its own, you have to tell it specifically I want to output something here, otherwise you could just do some processing, you could add one plus one... and not out put the results and do a calculation in there for the second for Mr. this has become more popular especially to a lot of experienced PHP developers has started to prefer having the shortcut but it's still a bad idea and we will talk about why just a second The other way that you could do it is to use ASP style tags. I think this is considered very poor form, instead of using the question mark, we use the percent sign.

ASP is Microsoft's version of PHP. It's what became asp.net. ASP was something that actually existed before asp.net. And this is the way that the tags look. They have the percents on either side. And again we have that equals there. Both of these options are something you can turn on and configure in your PHP INI file to allow them. otherwise you need to stick with the regular default PHP text. So why am I saying that this is a bade idea to create these kinds of texts. Well, it's specifically because they're enabled in the PHP INI file.

one of the wonderful things about PHP is that the code is portable. A version of PHP on Windows and MAC and Linux is all exactly the same. My code can just run on one, it can be moved to the other one and run their just as easily. But, if I make a choice to use a different style of tag and I require that the php.ini file be configured a certain way, then my code stops being portable. Now, it will no longer run on this other system because it's not configured correctly and I think that's a bad thing. If we just stick to the default standard tags, then our code will stay portable.

And that's going to be especially true if you start writing code that's going to be a plug in for existing application like Wordpress or Drupal or something. You want to be able to distribute that and have everyone be able to use it. So you want to be in the habit of using good, widely available, widely supported PHP tags. Otherwise, I think you're shooting yourself in the foot before you've even started. There are a couple of other points that I want to make about your php code. If we open up our myphpinfo.php file, I want to show you that the white space doesn't matter. White space inside the PHP code doesn't matter.

This is just as valid as what we had before. Same here, if we put more returns in here, tabs, spaces, those are all considered white space. And PHP doesn't care about those. It completely ignores it. It just executes the code as it goes through. And that's great, because it allows us, then, to use white space to help us to create readable code. We can indent things, we can group things together so that it's really nice and easy for us to read and follow. We don't have to worry how the white space is going to be interpreted. Not all languages work that way, and that's one of the nice things about PHP. The other thing I want to point out to you is notice that the command ends with a semicolon. That's part of the way that PHP helps to know when one command is over and another one is starting.

Since white space doesn't matter. It needs to have some reliable way to know this command is finished and I'm ready to move on to the next command. So every line is going to need to end in a semicolon. So get used to it. It's a habit you're going to have to get in, when working with PHP is to always put semicolons at the end of your lines. And there's one last thing I want to show you before we move on. Let's just close this up, we'll save it and close it. And inside our index.html file that we created earlier, if you don't have it, you can just create one, a nice, simple file inside here, index.html. Let's open that up, and let's just drop a little bit of PHP in there.

So open our PHP tags. You see that it auto closed it for me as well at the same time, that's nice. Phpinfo with my parentheses and then the semicolon, right? So that's the same little bit of PHP code that I had. Let's save it. We'll close that up. And let's now go into our browser and let's load that file up. Localhost, Kevin Scopeland. Index.html, that's the file I'm loading up. I get hello from my user directory, I did not get the result of that php function, it has nothing to do with the fact that there was other text in there at all.

In fact, if we view Source under web developer, I can choose, Page Source. And you can see that it actually just output the code itself. It didn't actually do any PHP processing on it. So why is that? I gave it my starting PHP tag and my ending PHP tag. Why didn't it process it? While that's because the file ends in .HTML. It's important that we have both of those things. The file needs to end in .PHP. That tells Apache, hey, be on the lookout for PHP tags. There may be PHP tags in this document.

And then when it sees a PHP tag It turns on it's PHP module. Starts processing the PHP until we close the PHP section. So it's important that we have both of these, right? If we start naming our files ending in something besides PHP, it's not going to see it as being a PHP file and try and do any processing on it. Now that we have the fundamentals of how to use PHP tags to embed PHP code into our document. Lets start trying to use that with dynamic text.

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This video is part of

Image for PHP with MySQL Essential Training
PHP with MySQL Essential Training

131 video lessons · 37985 viewers

Kevin Skoglund
Author

 
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  1. 4m 8s
    1. Welcome
      1m 0s
    2. Using the exercise files
      3m 8s
  2. 15m 6s
    1. What is PHP?
      3m 52s
    2. The history of PHP
      2m 51s
    3. Why choose PHP?
      4m 10s
    4. Installation overview
      4m 13s
  3. 54m 53s
    1. Overview
      2m 33s
    2. Working with Apache Web Server
      6m 56s
    3. Changing the document root
      7m 24s
    4. Enabling PHP
      6m 16s
    5. Upgrading PHP
      3m 30s
    6. Configuring PHP
      10m 3s
    7. Installing MySQL
      5m 46s
    8. Configuring MySQL
      7m 24s
    9. Text editor
      5m 1s
  4. 31m 25s
    1. Overview
      3m 27s
    2. Installing WampServer
      5m 46s
    3. Finding the document root
      2m 24s
    4. Configuring PHP
      8m 12s
    5. Configuring MySQL
      5m 45s
    6. Text editor
      5m 51s
  5. 19m 12s
    1. Embedding PHP code on a page
      6m 43s
    2. Outputting dynamic text
      5m 55s
    3. The operational trail
      2m 27s
    4. Inserting code comments
      4m 7s
  6. 1h 18m
    1. Variables
      7m 50s
    2. Strings
      4m 38s
    3. String functions
      8m 54s
    4. Numbers part one: Integers
      6m 27s
    5. Numbers part two: Floating points
      5m 25s
    6. Arrays
      10m 0s
    7. Associative arrays
      6m 37s
    8. Array functions
      6m 33s
    9. Booleans
      3m 50s
    10. NULL and empty
      5m 15s
    11. Type juggling and casting
      8m 27s
    12. Constants
      4m 43s
  7. 27m 37s
    1. If statements
      6m 0s
    2. Else and elseif statements
      4m 16s
    3. Logical operators
      7m 30s
    4. Switch statements
      9m 51s
  8. 42m 15s
    1. While loops
      8m 41s
    2. For loops
      5m 59s
    3. Foreach loops
      8m 16s
    4. Continue
      8m 28s
    5. Break
      4m 8s
    6. Understanding array pointers
      6m 43s
  9. 37m 25s
    1. Defining functions
      8m 25s
    2. Function arguments
      5m 32s
    3. Returning values from a function
      7m 33s
    4. Multiple return values
      4m 53s
    5. Scope and global variables
      6m 2s
    6. Setting default argument values
      5m 0s
  10. 20m 18s
    1. Common problems
      3m 47s
    2. Warnings and errors
      8m 36s
    3. Debugging and troubleshooting
      7m 55s
  11. 57m 57s
    1. Links and URLs
      5m 33s
    2. Using GET values
      5m 35s
    3. Encoding GET values
      8m 41s
    4. Encoding for HTML
      9m 26s
    5. Including and requiring files
      7m 40s
    6. Modifying headers
      6m 45s
    7. Page redirection
      6m 43s
    8. Output buffering
      7m 34s
  12. 1h 3m
    1. Building forms
      7m 28s
    2. Detecting form submissions
      5m 59s
    3. Single-page form processing
      7m 57s
    4. Validating form values
      10m 40s
    5. Problems with validation logic
      9m 54s
    6. Displaying validation errors
      7m 23s
    7. Custom validation functions
      6m 28s
    8. Single-page form with validations
      7m 25s
  13. 28m 5s
    1. Working with cookies
      2m 49s
    2. Setting cookie values
      5m 55s
    3. Reading cookie values
      6m 1s
    4. Unsetting cookie values
      4m 51s
    5. Working with sessions
      8m 29s
  14. 48m 39s
    1. MySQL introduction
      6m 43s
    2. Creating a database
      7m 41s
    3. Creating a database table
      7m 42s
    4. CRUD in MySQL
      5m 48s
    5. Populating a MySQL database
      7m 32s
    6. Relational database tables
      6m 40s
    7. Populating the relational table
      6m 33s
  15. 56m 4s
    1. Database APIs in PHP
      4m 51s
    2. Connecting to MySQL with PHP
      7m 45s
    3. Retrieving data from MySQL
      8m 47s
    4. Working with retrieved data
      6m 12s
    5. Creating records with PHP
      6m 58s
    6. Updating and deleting records with PHP
      9m 6s
    7. SQL injection
      3m 5s
    8. Escaping strings for MySQL
      6m 45s
    9. Introducing prepared statements
      2m 35s
  16. 35m 58s
    1. Blueprinting the application
      7m 19s
    2. Building the CMS database
      5m 14s
    3. Establishing your work area
      4m 38s
    4. Creating and styling the first page
      4m 22s
    5. Making page assets reusable
      6m 36s
    6. Connecting the application to the database
      7m 49s
  17. 32m 49s
    1. Adding pages to the navigation subjects
      5m 58s
    2. Refactoring the navigation
      6m 7s
    3. Selecting pages from the navigation
      6m 2s
    4. Highlighting the current page
      5m 26s
    5. Moving the navigation to a function
      9m 16s
  18. 1h 45m
    1. Finding a subject in the database
      9m 48s
    2. Refactoring the page selection
      10m 52s
    3. Creating a new subject form
      6m 55s
    4. Processing form values and adding subjects
      11m 20s
    5. Passing data in the session
      9m 16s
    6. Validating form values
      9m 40s
    7. Creating an edit subject form
      8m 30s
    8. Using single-page submission
      7m 44s
    9. Deleting a subject
      9m 44s
    10. Cleaning up
      10m 37s
    11. Assignment: Pages CRUD
      4m 30s
    12. Assignment results: Pages CRUD
      6m 10s
  19. 39m 26s
    1. The public appearance
      8m 52s
    2. Using a context for conditional code
      11m 37s
    3. Adding a default subject behavior
      6m 9s
    4. The public content area
      5m 51s
    5. Protecting page visibility
      6m 57s
  20. 1h 3m
    1. User authentication overview
      4m 3s
    2. Admin CRUD
      8m 41s
    3. Encrypting passwords
      7m 26s
    4. Salting passwords
      5m 42s
    5. Adding password encryption to CMS
      11m 54s
    6. New PHP password functions
      3m 13s
    7. Creating a login system
      11m 28s
    8. Checking for authorization
      5m 48s
    9. Creating a logout page
      5m 40s
  21. 2m 4s
    1. Next steps
      2m 4s

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