Easy-to-follow video tutorials help you learn software, creative, and business skills.Become a member

For loops

From: PHP with MySQL Essential Training

Video: For loops

In this movie, we'll look at For Loops. For loops are very similar to While Loops. They repeat a section of code, until a condition is met. But the syntax used for doing it is very different. Why have both, then? Well, probably because For Loops are the most classic kind of loop that there is, and they're used in many other programming languages. And some people prefer the compact syntax of For Loops. Let's take a look at this syntax now. A For Loop looks very similar at first, except for the expression part. Instead of having one expression in parenthesis, we're going to have three separated by semicolons. And each one's going to perform a different function. Expression 1, is going to be executed the first time only. It's like an initializing statement before the loop starts. Expression 2, is the test expression that's going to be checked at the start of each loop.

For loops

In this movie, we'll look at For Loops. For loops are very similar to While Loops. They repeat a section of code, until a condition is met. But the syntax used for doing it is very different. Why have both, then? Well, probably because For Loops are the most classic kind of loop that there is, and they're used in many other programming languages. And some people prefer the compact syntax of For Loops. Let's take a look at this syntax now. A For Loop looks very similar at first, except for the expression part. Instead of having one expression in parenthesis, we're going to have three separated by semicolons. And each one's going to perform a different function. Expression 1, is going to be executed the first time only. It's like an initializing statement before the loop starts. Expression 2, is the test expression that's going to be checked at the start of each loop.

Just like the expression that we had in the While Loop. Expression 3, is going to be executed at the end of every loop. Right after the loop finishes, right before it goes back and evaluates expression two again. Perhaps a better way to think of it is as initial test and each. There's the initial value, there's the test that its going to perform each time, and then each time through the last thing that its going to do is execute that each statement. Now, this syntax will work for a single line statement, but just like we saw with the While Loops. I think it's a good practice to always put curly braces around it. And if we have a multi-line statement those curly braces are required, we have to have it.

So, I'm going to suggest that it's the best practice for for you to always use those those curly braces any time you have a For Loop. And then we can tell what's being looped across. It's everything inside those curly braces. Alright, so I haven't really fully explained how initial test that each work can practice. Let's actually go to some code. So that we can try it out, and see how they work. So to start with, I'm going to open up basic.html. And I'll just do save as on this. And we're going to call this one forloops.php. We'll call it loops:for. Right now to begin with, I'm actually going to paste in a while loop, while loop example.

And I want you to see this while loop, because the way that it relates to the for loops, I think will help for loops make a lot more sense to you. So, let's write our for loop now, right below it and let's try to accomplish the exact same thing that the while loop does. So, we're going to have our PHP tags, and then let's start with for, and then we have our initializing statement. Right, that's the first argument. The thing that we're going to do at the beginning is initialize. So, we did some initialization up here, look at this. Count equals 0. We initialized the value count before we did the while. Well, that's exactly what we want to do here.

That's our initialization. Here it was on a separate line. Here it's inside the arguments to the loop. Now, right after that, we need a semicolon, so we have a second statement after that. In the next statement, is going to be the expression of what we do each time through that. And I told you that was exactly like the while loop. So we're just going to copy that, we're going to put that in there. And then, the last we'll remember is something that happens at the end of every loop, right before it goes back again. Well, lets look at our while loop. What are we doing each and every time? We're incrementing, and that's the probably the most common thing it happens in this third expression. You can also decrements it can be count minus minus. Or it can do something much more complicated.

It could divide by two, or multiply by four. All sorts of things can go there. But typically, the most common one is just to simply increment. So, now that we have that, we just need to put our curly braces, and then what are we actually going to loop? What's the business that we want to do each time we go through this loop? Well there it is right there. We're just going to take count and then output it. So, some people like this syntax better. We're doing all the initialization. We're doing the incrimenting. We're doing the testing all in one line. It's all kind of get that business out of the way, right there at the start. And then what's inside our loop is a little bit more isolated. It has nothing to do with the business of looping.

It really is just the thing that we want it to do each time through. So, let's try it, just to make sure that this works. Let's give ourselves a br tag here just, so we can separate that out from the one before it. Let's go to Firefox and instead of while loops, we're now going to open up for loops. And there we go, see it did the exact same thing right underneath it. Now just like we had with while loops, we can do all the same things. You want to watch out for infinite loops and you can have if statements inside here that do conditional operations. So as another example, let's look at the loop that I gave you as a assignment at the end of the while loop section.

Something to do on your own. Let's try those results here. So we'll do br tag, and then I'm going to paste in a for loop. It's going to start out with count equals to one. Count is while it's less than 20, it's going to keep executing. And each time it's going to increment count. Now, just to see the difference. Let's just try it in reverse. Let's say, count is equal to 20 to start with. And as long as count is greater than zero, then were gona keep going. So were going to count down, and then we're going to count down that I need to do minus minus here at the end. You also could do minus equals 1 if you wanted.

That does the exact same thing. Now, here's the, the heart of my loop. If count modulo 2 is equal to 0. That means if I take count and divide it by 2, if there is no remainder, right? If it divides evenly, then it will be equal to zero. Nothing left over, then I'll know that it's an even number. Otherwise it's an odd number. All right, so let's just try that out. Let's go over here to Firefox. Let's reload. There it goes, 20 is even, 19 is odd. All the way down until we get to one is odd. So, hopefully, you see how that works, and you see the relationship between a while loop and a for loop. How they're basically doing the exact same thing? It's just a different syntax and a different way to write it. Use whichever one feels most comfortable to you. They both accomplish exactly the same thing, it's just a matter of personal style and taste.

Show transcript

This video is part of

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

131 video lessons · 32808 viewers

Kevin Skoglund
Author

 
Expand all | Collapse all
  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

Start learning today

Get unlimited access to all courses for just $25/month.

Become a member
Sometimes @lynda teaches me how to use a program and sometimes Lynda.com changes my life forever. @JosefShutter
@lynda lynda.com is an absolute life saver when it comes to learning todays software. Definitely recommend it! #higherlearning @Michael_Caraway
@lynda The best thing online! Your database of courses is great! To the mark and very helpful. Thanks! @ru22more
Got to create something yesterday I never thought I could do. #thanks @lynda @Ngventurella
I really do love @lynda as a learning platform. Never stop learning and developing, it’s probably our greatest gift as a species! @soundslikedavid
@lynda just subscribed to lynda.com all I can say its brilliant join now trust me @ButchSamurai
@lynda is an awesome resource. The membership is priceless if you take advantage of it. @diabetic_techie
One of the best decision I made this year. Buy a 1yr subscription to @lynda @cybercaptive
guys lynda.com (@lynda) is the best. So far I’ve learned Java, principles of OO programming, and now learning about MS project @lucasmitchell
Signed back up to @lynda dot com. I’ve missed it!! Proper geeking out right now! #timetolearn #geek @JayGodbold
Share a link to this course

What are exercise files?

Exercise files are the same files the author uses in the course. Save time by downloading the author's files instead of setting up your own files, and learn by following along with the instructor.

Can I take this course without the exercise files?

Yes! If you decide you would like the exercise files later, you can upgrade to a premium account any time.

Become a member Download sample files See plans and pricing

Please wait... please wait ...
Upgrade to get access to exercise files.

Exercise files video

How to use exercise files.

Learn by watching, listening, and doing, Exercise files are the same files the author uses in the course, so you can download them and follow along Premium memberships include access to all exercise files in the library.


Exercise files

Exercise files video

How to use exercise files.

For additional information on downloading and using exercise files, watch our instructional video or read the instructions in the FAQ.

This course includes free exercise files, so you can practice while you watch the course. To access all the exercise files in our library, become a Premium Member.

Are you sure you want to mark all the videos in this course as unwatched?

This will not affect your course history, your reports, or your certificates of completion for this course.


Mark all as unwatched Cancel

Congratulations

You have completed PHP with MySQL Essential Training.

Return to your organization's learning portal to continue training, or close this page.


OK
Become a member to add this course to a playlist

Join today and get unlimited access to the entire library of video courses—and create as many playlists as you like.

Get started

Already a member?

Become a member to like this course.

Join today and get unlimited access to the entire library of video courses.

Get started

Already a member?

Exercise files

Learn by watching, listening, and doing! Exercise files are the same files the author uses in the course, so you can download them and follow along. Exercise files are available with all Premium memberships. Learn more

Get started

Already a Premium member?

Exercise files video

How to use exercise files.

Ask a question

Thanks for contacting us.
You’ll hear from our Customer Service team within 24 hours.

Please enter the text shown below:

The classic layout automatically defaults to the latest Flash Player.

To choose a different player, hold the cursor over your name at the top right of any lynda.com page and choose Site preferencesfrom the dropdown menu.

Continue to classic layout Stay on new layout
Exercise files

Access exercise files from a button right under the course name.

Mark videos as unwatched

Remove icons showing you already watched videos if you want to start over.

Control your viewing experience

Make the video wide, narrow, full-screen, or pop the player out of the page into its own window.

Interactive transcripts

Click on text in the transcript to jump to that spot in the video. As the video plays, the relevant spot in the transcript will be highlighted.

Are you sure you want to delete this note?

No

Your file was successfully uploaded.

Thanks for signing up.

We’ll send you a confirmation email shortly.


Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

Keep up with news, tips, and latest courses with emails from lynda.com.

Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

   
submit Lightbox submit clicked
Terms and conditions of use

We've updated our terms and conditions (now called terms of service).Go
Review and accept our updated terms of service.