Does WordPress function replace_hello() exists?

Question

I was looking at this website: https://chandanpandey.com/author/irinampapuc/page/2/ and one of the PHP code solutions in it is nagging at me. The problem is How would you change all the occurrences of “Hello” into “Good Morning” in post/page contents, when viewed before 11AM? The author has an answer that looks like this:

<?php

function replace_hello(){

}

I have Googled this function and the only function I know of that can replace a string is the PHP str_replace() function.

Can anyone confirm the above function is an actual function? In other words is function replace_hello() or function replace_welcome() actually a valid function and where (if at all) in the WordPress Codex or any documentation can I locate to learn more about it?

Answer 1

This is custom function the author uses to show how to use the_content filter. If you look at the line after the function add_filter('the_content', 'replace_hello'); this is saying to call the custom function replace_hello when encountering the the_content filter