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Inserting code comments

From: PHP with MySQL Essential Training

Video: Inserting code comments

In this movie, we're going to learn how to insert code comments into our PHP. We don't want to become simply capable developers, we want to become good developers. And in order to do that, we need to learn about code comments, something that's very important in any programming language. You want to add comments to your code so that you or someone else coming to look at the code later. Can quickly understand what your code is trying to accomplish, and understand the approach that you took. Comments take additional time to write, but they pay off and save you time later. In PHP, there are a couple of ways we can write comments.

Inserting code comments

In this movie, we're going to learn how to insert code comments into our PHP. We don't want to become simply capable developers, we want to become good developers. And in order to do that, we need to learn about code comments, something that's very important in any programming language. You want to add comments to your code so that you or someone else coming to look at the code later. Can quickly understand what your code is trying to accomplish, and understand the approach that you took. Comments take additional time to write, but they pay off and save you time later. In PHP, there are a couple of ways we can write comments.

We can make single line comments by simply opening PHP tags, and then putting in // followed by our comment, single Line comments are like this. Or we could use a pound sign. Or like this but that is less common. Mostly you're going to see people using the slash slash in front of it and that's what I'll be using throughout this title. Now lets just save that document real quick and lets go over here and lets reload this hello world page in our browser.

So there's the page, let's do view source on it, web developer, and page source. And you can see the comments do not show up, right, just the things that I echoed out, just the output. So these comments are not output into our HTML. And they are not processed as PHP, they're just simply ignored. They're there for our benefit only. And I want you to note two things about them. First of all, this only works inside PHP tags. right? If we did it up here, then that's just html that we're writing, that's just text that will be output, so we can't put them there.

And also this technique doesn't work for double-line. So for example, if we have double-line comments that keep going, oh wait a minute. Notice that TextMate actually helpfully colored it a different color for me. The brown text color indicates that it's a comment. The blue is indicating that it's going to be, try and process this as some kind of PHP. And I'm going to get an error. Now, we could just put more // in front of it. That's certainly valid to do your comments that way. But I also want to show you that you can do double-line comments by putting A slash with an asterisk after it.

So double line comments are written like this, so that you can keep typing. I'll just indent a little bit and typing. And you can do that all the way until you type another asterisk, and a forward slash. So everything in between these, is all going to commented out. It's a little bit like turning on and off the PHP tags for PHP processing. We're saying this whole thing is a comment until you get to the ending comment marker just assume that we're still in comment mode.

And this is great because it allows us to type entire paragraphs describing what our code does. And of course one thing I want to a caution you about is you don't want to try to put a multi line comment inside another comment because as soon as you get to the first ending slash, alright, even if we have another starting slash, test. Right it's going to close it and turn off commenting mode, they're not nested, so two turn ons does not equal two turns offs, right, so as soon as we get to an off that's it, it's out of comment mode, and let's save that and then let's just comeback over here and reload the page one more time and take a look.

View Source. And you can see that it doesn't show up there either. Comments are super important to writing good code. They can be hard to be disciplined about it. You get caught up in writing the code, and often you forget to leave yourself comments. But once you start programming a lot you'll realize that comments are going to save you a lot of time, not now, but 10 weeks from now. When you come back to the code. You can't remember what you were trying to do or why you chose a certain approach. It's one of those things where investing a little bit of time in the beginning is going to save you lots of time later on. And comments are especially friendly if there's ever someone else who's going to be working with your code, because they don't know what you were thinking. They don't know The reasoning that you went through to arrive at a solution to a certain problem, but your comments can make it clear to them. So I'd like you to make a promise to yourself right now that you're going to try and put as many comments in your code as you can. Especially while you're still learning PHP.

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This video is part of

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

131 video lessons · 38041 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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