Find and Replace Words in a WordPress Post

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This PHP function will search for a particular string of text in a WordPress post and replace it with alternative text of any kind.

If you’re just getting into the affiliate business, this is a great way of instantly monetising your blog via specific keywords. If you’ve ever written about Thesis, you could, via the function below, automatically convert every instance of the word “thesis” into an affiliate link.

Not unlike WordPress shortcode, it’ll permit you to globally change one piece of text into another. In this case, thought, we’re using the text itself rather than structured shortcode.

Loosely based on the principles applied in the post, “Pirate Day – WordPress Shortcode, we’re creating an array of both our original word and text to replace it. In fact, the Pirate post can be used almost as we’ve done; the different being that this function will retroactively alter defined words anywhere in your posts.

You’ll find far more useful plugins at WordPress.org… but this will be enough to get you started.

Copy the following code into your theme’s functions.php file.

function replace_custom_word($text){
    $replace = array(
	'thesis' => 'Thesis',
	'studiopress' => 'Studiopress'
    );
    $text = str_replace(array_keys($replace), $replace, $text);
    return $text;
}

add_filter('the_content', 'replace_custom_word');
add_filter('the_excerpt', 'replace_custom_word');

The function is case-SenSItiVe. If you would like to create a case-insensitive version of the above function, replace str_replace with str_ireplace.

The output

I included the function long enough on this site to take a screenshot. The above code will render the word “Thesis” as follows:

I’ve applied a basic style but you can obviously do whatever you want to it – including link titles etc.

Interested in researching the code?

If you’re interested in the code above, you’ll want to check out the following functions.

WordPress Functions

the_content : the_content displays the contents of the current post.

the_excerpt : the_excerpt displays the excerpt of the current post with [...] at the end, which is not a “read more” link.

the_filter : the_filter Filters are the hooks that WordPress launches to modify text of various types before adding it to the database or sending it to the browser screen. Plugins can specify that one or more of its PHP functions is executed to modify specific types of text at these times, using the Filter API.

PHP Functions

array, str_replace, array_keys

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