In this short tutorial, we will learn to how to create a simple WordPress plugin step by step and to have the plugin activated from the WordPress dashboard. Important names are highlighted to help ease the tutorial navigation.

To write a calculator WordPress plugin, follow these steps:

1. Set up the plugin structure:
   1. Create a new directory inside the wp-content/plugins directory of your WordPress installation. Name it something like calculator-plugin.
   2. Inside the calculator-plugin directory, create a new file named calculator-plugin.php. This will be the main plugin file.
2. Open the calculator-plugin.php file in a text editor and add the following code to set up the plugin: <?php /** * Plugin Name: Calculator Plugin * Plugin URI: https://www.example.com/calculator-plugin * Description: Simple calculator plugin for WordPress. * Version: 1.0.0 * Author: Your Name * Author URI: https://www.example.com * License: GPL v2 or later * License URI: https://www.gnu.org/licenses/gpl-2.0.html */ // Plugin code goes here
3. Define the plugin functionality: Inside the calculator-plugin.php file, add a function that will handle the calculator functionality. For example: <?php function calculator_shortcode($atts) { // Shortcode logic goes here }
4. Register a shortcode: Still inside the calculator-plugin.php file, add the following code to register a shortcode that will be used to display the calculator: add_shortcode('calculator', 'calculator_shortcode');
5. Implement the calculator logic: Inside the calculator_shortcode function, implement the calculator logic using HTML and PHP. For example: <?php function calculator_shortcode($atts) { ob_start(); ?> <form action="" method="POST"> <input type="number" name="num1" placeholder="Enter number 1" required> <input type="number" name="num2" placeholder="Enter number 2" required> <select name="operation" required> <option value="+">Addition</option> <option value="-">Subtraction</option> <option value="*">Multiplication</option> <option value="/">Division</option> </select> <button type="submit">Calculate</button> </form> <?phpif ($_SERVER['REQUEST_METHOD'] === 'POST') { $num1 = $_POST['num1']; $num2 = $_POST['num2']; $operation = $_POST['operation'];$result = 0;switch ($operation) { case '+': $result = $num1 + $num2; break; case '-': $result = $num1 - $num2; break; case '*': $result = $num1 * $num2; break; case '/': $result = $num1 / $num2; break; }echo "<p>Result: $result</p>"; }return ob_get_clean(); }
6. Save the calculator-plugin.php file.
7. Activate the plugin:
   1. Log in to your WordPress admin dashboard.
   2. Go to the "Plugins" page.
   3. Find the "Calculator Plugin" in the list of plugins and click "Activate".
8. Use the calculator shortcode:
   1. In the WordPress editor, create a new page or post where you want to display the calculator.
   2. Add the following shortcode to the content area: [calculator]
   3. Save or publish the page.