Repeating code using Loops

There are many times when you need to repeat code over and over again. The WordPress main loop is a big one that we can all relate to. The premise of it is this:

• The while controls the code block, meaning the code does not run unless the conditional expression is true.
• have_posts() checks to see if there any more posts to process
• The code runs when there are more posts to run, meaning have_posts() returned true.
• Then it loops back around to the while again. Repeat.

Therefore, when using the while, the loop will continue looping (repeating the code within its code block) until the conditional expression is false. You can build more complex conditional expressions, as you need to run the loop.

PHP provides many more looping constructs including foreach and for. You use the foreach to loop through the items within a collection, meaning an array, or an object. For an array, you can pull out each element and then use it within the code block.

Why do we repeat with loops?

There are a couple of reasons. But here are the primary ones.

The first reason is to save yourself from having to type the same code over and over again. Why would you do that? If the same lines of code need to run multiple times, it doesn’t make sense to type that many times. No, that’s redundant. It’s also more code for you to test and maintain. Yuck. Looping lets you write it one time and then repeatedly run it over and over again.

The second reason is dynamic information. When you write the code, you don’t know how many elements will be in the array or how many posts there are for a given web page. Right? For example, for the main loop, if you are on the Posts Page, the number of posts to be processed will vary. Using a loop, you can iterate and decide at runtime how many times to run the loop.

Challenge Yourself

If there are 6 posts to be displayed on the Blog page, how many times will the main WordPress loop run?

It will loop through all 6 of the posts and run the code within the theme to process each one.

If an array has 12 elements in it, when using a `foreach`, how many times will its code block run?

12 times. A foreach loops through each element in the array, pulling it out for processing. Since there are 12 elements, the code will run 12 times within the loop.

For the above code, will the `while` loop run the code block?

No. Why? The comment says this post does not have a featured image. That means the WordPress function has_post_thumbnail() will return false. The loop only runs when the conditional expression is true.

References

Here is a link to PHP type casting for you.