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Introducing functions.php

From: WordPress 3: Building Child Themes

Video: Introducing functions.php

At the core of all WordPress themes lies a file named functions.php. As the name suggests, the functions.php file contains core functions that make the theme work. These functions range from simple bits of code that activate code WordPress functionality to advanced functions you can modify to add new functionality and new features to the theme and to the site. Understanding the role and function of functions.php will enable you to go from simply messing with the template files in CSS to adding whole new levels of awesomeness to your site.

Introducing functions.php

At the core of all WordPress themes lies a file named functions.php. As the name suggests, the functions.php file contains core functions that make the theme work. These functions range from simple bits of code that activate code WordPress functionality to advanced functions you can modify to add new functionality and new features to the theme and to the site. Understanding the role and function of functions.php will enable you to go from simply messing with the template files in CSS to adding whole new levels of awesomeness to your site.

Yes, I said it: awesomeness. Opening functions.php for the first time can be a bit of a shock, because it's a very complicated file--or at least it appears to be a very complicated file--and is also chock-full of lots of stuff that doesn't seem to be related to each other in any sensible way. The good theme about the twentytwelve theme and the other core themes from WordPress is that they come heavily documented, meaning there's lots of explanations inside the files that explain what these files do.

And that's especially true for functions.php in twentytwelve. There is lots of documentation explaining what's going on throughout the functions file. If you look at the functions file, I'll show you some examples of what this file actually does. If you skip down to line 61, you'll see here we have a simple function called add_theme_support. This function adds different types of theme support, for example post-formats. So here you can see post-formats are activated and then there is a list of what types of post formats are activated, because there are several different types of formats you can activate if you want to and twentytwelve uses five of these post formats.

Directly underneath, you have this function, register_nav_menu, where the different nav menus are registered, so that you can creates menus inside WordPress Admin. And below that, you have add_theme_ support for a custom background, so that you can set different custom background colors for your theme from within WordPress Admin. Moving down the file, you'll see on line 195 we have the function that creates all the widgetized areas. Here you can see we have three widgetized areas. We have Main Sidebar, and then we have First Front Page Widget Area and Second Front Page Widget Area.

So when you ask where the widgets come from, this is actually where they come from, functions.php. And if we scroll further down, to line 258, you'll see where the comments come from. This is actually after the template that creates the comments section on your site. So when you want to work with comments you need to work with the code inside function.php and also inside comments.php. What I have shown you here is just a small selection of what's in functions.php, and we're now going to work with function.php to augment what's in there already and also add new stuff to the file.

functions.php holds a lot of behavioral elements of a WordPress theme, and understanding how it works and how to interact with it will allow you to make truly advanced themes that work the way you want them to. Fortunately, the 2012 developers have left excellent documentation right in functions.php file, so it's easy for you to figure out what's going on.

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This video is part of

Image for WordPress 3: Building Child Themes
WordPress 3: Building Child Themes

45 video lessons · 32936 viewers

Morten Rand-Hendriksen
Author

 
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  1. 6m 59s
    1. Welcome
      1m 6s
    2. Using the exercise files
      1m 34s
    3. What you need to know before watching this course
      1m 29s
    4. Getting the right tools for theme creation
      2m 50s
  2. 17m 2s
    1. What is a WordPress child theme and when should you use it?
      2m 38s
    2. Picking a parent theme
      3m 55s
    3. Making sure you have the Twenty Twelve parent theme
      1m 50s
    4. Creating and activating a basic child theme
      4m 20s
    5. Importing parent theme styles
      4m 19s
  3. 16m 2s
    1. Using the developer tools
      3m 53s
    2. Modifying existing styles
      4m 24s
    3. Adding space between paragraphs
      4m 7s
    4. Changing font family styles
      3m 38s
  4. 31m 47s
    1. Understanding the WordPress template hierarchy
      3m 12s
    2. Modifying existing templates
      2m 33s
    3. Moving the header image
      4m 29s
    4. Adding Related Posts feature to posts
      6m 26s
    5. Creating custom page templates
      5m 43s
    6. Using conditional statements for customized effects
      5m 41s
    7. Creating custom header, footer, and sidebar templates
      3m 43s
  5. 17m 5s
    1. Understanding the different index pages and what they do
      4m 6s
    2. Adding author, date, and time information to the index loop
      7m 15s
    3. Changing the appearance of category index pages
      5m 44s
  6. 43m 5s
    1. Introducing functions.php
      3m 24s
    2. Overriding existing functions
      3m 23s
    3. Adding pagination to index pages
      5m 49s
    4. Adding to existing functions
      3m 21s
    5. Adding a new footer menu to Twenty Twelve
      6m 24s
    6. Adding a new widgetized area to pages
      4m 9s
    7. Adding static content to the sidebar
      7m 44s
    8. Replacing existing functions
      2m 36s
    9. Adding a Google font through a function
      6m 15s
  7. 10m 24s
    1. Adding new featured image sizes
      5m 41s
    2. Adding featured images to posts and pages
      4m 43s
  8. 31m 1s
    1. Adding a welcome message to the front page
      1m 22s
    2. Displaying page content in an index page
      7m 42s
    3. Hooking in a featured image
      4m 34s
    4. Making the welcome message responsive
      6m 27s
    5. Restricting content to the first page of the blog
      4m 22s
    6. Adding a jQuery function to show or hide the welcome message
      6m 34s
  9. 10m 23s
    1. Adding a custom favicon
      3m 58s
    2. Adding a custom screenshot
      2m 29s
    3. Adding footer information
      3m 56s
  10. 7m 14s
    1. What to do when a child theme crashes your website
      4m 38s
    2. Updating parent and child themes
      2m 36s

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