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PHP with MySQL Essential Training
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Arrays


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PHP with MySQL Essential Training

with Kevin Skoglund

Video: Arrays

Arrays are a common feature in many programming languages. Arrays are going to be extremely useful for helping us to keep information organized. So, what is an array? An array is an ordered, integer-indexed collection of objects. That's a fancy way of saying that we can take objects, like strings and integers and put them into a group and then keep their position in that group in the same order, so that we can refer to those objects by their positions. We can tell the array, give me back the first object, give me the fifth object, and so on, because the objects are going to be indexed according to what position they hold in the array.
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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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PHP with MySQL Essential Training
14h 24m Beginner Jun 04, 2013

Viewers: in countries Watching now:

PHP is a popular, reliable programming language at the foundation of many smart, data-driven websites. This comprehensive course from Kevin Skoglund helps developers learn the basics of PHP (including variables, logical expressions, loops, and functions), understand how to connect PHP to a MySQL database, and gain experience developing a complete web application with site navigation, form validation, and a password-protected admin area. Kevin also covers the basic CRUD routines for updating a database, debugging techniques, and usable user interfaces. Along the way, he provides practical advice, offers examples of best practices, and demonstrates refactoring techniques to improve existing code.

Topics include:
  • What is PHP?
  • Installing and configuring PHP and MySQL
  • Exploring data types
  • Controlling code with logical expressions and loops
  • Using PHP's built-in functions
  • Writing custom functions
  • Building dynamic webpages
  • Working with forms and form data
  • Using cookies and sessions to store data
  • Connecting to MySQL with PHP
  • Creating and editing database records
  • Building a content management system
  • Adding user authentication
Subjects:
Developer Servers Programming Languages Web Development
Software:
MySQL PHP
Author:
Kevin Skoglund

Arrays

Arrays are a common feature in many programming languages. Arrays are going to be extremely useful for helping us to keep information organized. So, what is an array? An array is an ordered, integer-indexed collection of objects. That's a fancy way of saying that we can take objects, like strings and integers and put them into a group and then keep their position in that group in the same order, so that we can refer to those objects by their positions. We can tell the array, give me back the first object, give me the fifth object, and so on, because the objects are going to be indexed according to what position they hold in the array.

One good way to think about arrays is that they're like those expanding file folders that you can buy to put your bills in. You might put your electric bills in the first pocket and your phone bills in the second pocket, your mortgage payments in the third pocket, and so on. You have a preset order and you can put things in pockets and take them out again. Put this paper into the third pocket. Show me the paper that's in the fifth pocket. That's the way that arrays work. Now there's no limits to how many pockets your array can have. At least none that you're going to need to worry about. And a pocket contained anything that a variable can contain. A string, a number, even another array.

In fact, a pocket can be just plain empty and an array can be assigned to a variable, which makes it easy for us to reference a large collection of information by using a single, simple variable name. Let's try and example. Let's create a new page for ourselves. We'll open up basic.html, do Save As, and let's call this arrays.php. I'll change the title to be Arrays and let's create our first PHP tags here. Now, the first array that I'm going to create, I'm going to assign to the variable: numbers. Now the way that you define an array is array() and that's it. We now have defined an empty array and assigned it to numbers. There's no objects inside this array, it's just empty. We can put a series of objects in our array and separate them by using commas. For example, I'll put in some numbers.

4,8,15,16,23,42. So now, I have an array that consists of numbers. And those numbers are always going to stay in the order that I've put them there. They're going to stay in that exact order. And that way, I can refer to them by position, when I want to get them back out. So let's try that. Let's see how we retrieve something from an array. We'll use echo. We're going to reference the variable numbers because that's what's pointing to our array. It references it. And then we're going to use square brackets.

And inside those square brackets, we're going to provide the index that we want it to return. In this case, the index will be the position that's returned what's in position one. Put our semicolon at the end, and let's bring that up in our browser an take a look. Go back to Firefox and instead of floats, let's bring up arrays. So there it is. It returned an object to us, and the object that it returned was 8. Now, wait a minute. If you go back and you look, 8 is what we would've expected was in the second pocket. And that brings up a very important point about arrays that we must always keep in mind.

Arrays are numbered starting from zero. The first pocket is indexed as zero. The second pocket is indexed as one. It'll take some getting used to if you haven't worked with arrays before but that's how arrays work in almost every single programming language, not just in PHP. So if we change our index to be zero and then we go back and we reload our page. We'll get back the first item, which is 4. So, the first item is indexed with 0. You really want to make sure you drill this idea in your head. First pocket in array, the first item in array, the first value, is always going to be referred to by using the index 0.

And as I said, an array can contain lots of different types of objects. So, for example, we can have a mixed type object. We'll call it mixed, and inside there, we'll have an array. And in that array, let's put the number 6, the word fox, followed by the word dog, followed by another array. Then in that array we'll put x and y and z. So you see how that works? It doesn't matter what kind of objects we put in there. It can be integers, it can be strings, it can even be other arrays. Any valid type in PHP can go inside an array.

So lets now echo back one of those values. Lets do echo from mixed. And let's ask it for what's in number 2. So let's put some BR tags in here just to clean this up a bit; put one up here as well. And let's also ask it, before we go back and reload the page, for what is in pocket number 3. Now, we know what number 2 should be, right? because we know that they start counting at 0, so you can go down the numbers and say, 0, 1, 2, and figure out what's going to be in this second position, the second index. Let's bring that up in a browser and take a look and see if you were right. And it returned dog to us.

Now, notice here, we got a notice, array to string conversion is what's happening, and it returned to us Array. So when we ask for the third item, they came back and said it's an array. That's what I see there. I see an array. And it used array to string conversion to try and give us an output for that, rather than ouput the entire array. Now, if we wanted to see the entire array, we can do that. Let's just try this real quick. Echo, let's look at the array itself. See what that gives us? That comes back and gives us array as well.

(SOUND) Instead, it's really helpful when you're working with arrays to use print_r. That stands for print-readable. And that's a nice way for debugging to see what's inside of our arrays. Now, it's not something we would ever want to show to our users. It's really just for our purposes. With, with our array, hopefully, we've pulled the data out of the array that we want. And we're not going to run into this problem. But let's just do print r on mixed, and see what that gives us back. You see? That's gives us something that's readable now.

It shows us this is an array. And here's what that array contains. And you can see the indexes in front of each one. This is index 0, this is index 1, and so on. Even nicer is if you put the pre tags around it for the HTML. (SOUND) And now, look at that. Now, they're indented and everything. It makes it nice and easy for us to follow and see what's inside that array. Now, what if we wanted to get a value out of this array? Right? So, we're basically looking inside one array, and then from that, pulling another value out of that array.

We can do that. Let's just go up here and copy this line. We'll bring it down here. And after we get back, the nested array which is in position 3, then we'll just going to ask for what's in position 1 right after it. Square bracket followed by square bracket. Let's go take a look. There it is, it returned Y to us. See how that works. I'm just going to get rid of these warnings up here by just commenting these lines out. So we don't hit those anymore. Now what about adding things to our array.

Alright now we were able to pull things out of the array but we want to be able to assign values into it. We don't want to have to redefine the whole array each time. We can put things into pockets by simply saying mixed, and we'll say at position two equals cat. That's it, that's all there is to it. You just say alright, at position 2, set this value, put that in there. It's just a simple assignment operator. Let's do another one. I'll just copy this line and let's say that at position 4, we're going to put mouse.

Now wait a minute, there is no position 4. Position 3 was this item here. So position 4, it's okay to refer to it. It's going to put an item in that fourth position for us. So let's go ahead and take a look and while we're at it, let's move our print the array down to the bottom. And that will allow us to just see everything that's in there. So here it is. See cat up here? And mouse, down here in the fourth position? There's also another way. If you don't know how long something is and you just want it to go to the end, you can just make it be blank.

Let's do horse. And that will put it at the end. It's appending it to the end. Whatever the last index is, this is going to add it to the end of it. Take a look at that, and so there it is, it put horse in the fifth position. So the power of arrays, is that a set of information can be referenced by a single variable. Imagine if we have one thousand email addresses. We wouldn't want to create one thousand variables for those, instead we can assign all of them to an array, and then use one easy to reference variable to pull up each email address by its index. The other thing that's powerful about arrays is that they keep their information in the same order unless we change it. Whatever we put in the first pocket stays in the first pocket. So, arrays are good for keeping ordered lists.

We can sort those 1000 email addresses and then they'll be kept in that order for us by the array. You can imagine how arrays are going to stop helping us when we start pulling records and data out of our database. We can retrieve 50 customer records sorted alphabetically by last name and store them in the array. And they'll stay sorted in that array by last name. The one last thing that I want to mention to you, is that PHP 5.4, which most of you are probably running, 5.4 or later, has a short array syntax. Instead of writing out the word array, we can just use square brackets to define it.

So an array can be equal to 1,2,3. This doesn't work in 5.3 or earlier. So because of that, I'm going to stick with the long notation, so that anyone taking this training who happens to be using an earlier version won't get stuck. But if I were writing PHP for myself, well, I would definitely use this shorter notation. So it's up to you which one you want to use. Array with the parentheses around it is probably going to start becoming rarer over time. But right now the square bracket is a little bit new. So you aren't going to see it in a lot of older code, especially if they still need to support older versions of PHP.

But you should be able to see it in both forms and recognize it as an array.

Find answers to the most frequently asked questions about PHP with MySQL Essential Training.


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Q: This course was revised on 6/4/2013. What changed?
A: The old version of this course was 6 years old and it was time for a complete revision, using PHP 5.4. (The tutorials will work with any version of PHP and covers any differences you might encounter). The author has also added updated installation instructions for Mac OS X Mountain Lion and Windows 8. The topics and end project are the same, but the code is slightly different. It also addresses frequently asked questions from the previous version.
 
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