A WordPress plugin shortcode template on both oop and procedural approach. Visit https://www.davidangulo.xyz/ for more information.

index-oop.php

<?php 
/* 
Plugin Name: Example Shortcode Plugin 
Plugin URI: https://wordpress.org/plugins/ 
Description: Just another example shortcode plugin. 
Version: 1.0.0 
Author: David Angulo 
Author URI: https://www.davidangulo.xyz/ 
*/ 

class myShortCode { 
	public function __construct() { 
		add_shortcode("my_custom_shortcode",array($this,"myShortCodeRender")); 
	} 

	public function myShortCodeContent() { 
		echo "Hello! I am a custom shortcode."; 
	} 

	public function myShortCodeRender() { 
		ob_start(); 
		$this->myShortCodeContent();
		return ob_get_clean();
    }
}

$object = new myShortCode;

//Visit the tutorial for more information
//https://www.davidangulo.xyz/website-development/how-to-create-custom-wordpress-shortcode-plugin-from-scratch/

index-procedural.php

<?php
/*
Plugin Name: Example Shortcode Plugin
Plugin URI: https://wordpress.org/plugins/
Description: Just another example shortcode plugin.
Version: 1.0.0
Author: David Angulo
Author URI: https://www.davidangulo.xyz/
*/

function myShortCodeContent() {
    echo "Hello! I am a custom shortcode.";
}

function myShortCodeRender() {
    ob_start();
    myShortCodeContent();
    return ob_get_clean();
}

add_shortcode("my_custom_shortcode","myShortCodeRender");

//Visit the tutorial for more information
//https://www.davidangulo.xyz/website-development/how-to-create-custom-wordpress-shortcode-plugin-from-scratch/