WPAmaNuke

Sometimes we need to create wordpress theme child for modification css only. We need to create child theme because regular update on parent theme so we don’t need to change code if there is new update. Here is the way to create child theme for Nineteen Child Theme :

• Create folder nineteen-child
• Create file style.css
• Create file functions.php

That’s very simple. For the structure of sytle.css is like this :

/*
Theme Name: Twenty Nineteen Child
Theme URL: http://wpamanuke.com/
Description: Twenty Seventeen Child Theme
Author: WPAmaNuke
Author URL: http://wpamanuke.com/
Template: twentynineteen
Version: 1.0.0
Text Domain: twentynineteen-child
*/ 
/* Custom CSS goes after this line */

.entry .entry-title a {
	color:#ff0000;
}

For modifying css , you need to use firefox web developer inspector or chrome devtools and do some experiment

To include parent style.css you need to create file functions.php and add code like this :

<?php

	add_action( 'wp_enqueue_scripts', 'tnt_enqueue_parent_styles' );

	function tnt_enqueue_parent_styles() {
	   wp_enqueue_style( 'parent-style', get_template_directory_uri().'/style.css' );
	}

?>

To Create WordPress Plugin you need to know how basic php , css and html works.
Here is some function which ussually i used for wordpress plugin.

PREFIX

It’s suggested to prefix your function and variable. For example using mfp (My First Plugin). Here is the example $mfp_string , mfp_function.

DIR and URL

You can detect directory and url WordPress Plugin using function plugin_dir_path( FILE ) and plugin_dir_url( FILE ).
I ussually use constant some constanta like this :

define( 'MFP_DIR' , plugin_dir_path( __FILE__ ) );
define( 'MFP_URL' , plugin_dir_url( __FILE__ ) );

HOOK

Hook is function so you don’t need to change the core code. There are 2 hooks : action and filter.

ACTION

Here are some function which you need to know : do_action , add_action and remove_action

DO_ACTION

For example your index.php in theme like this

<?php
	do_action( 'mfp_header_before' );
	echo '<div>HEADER</div>';
	do_action( 'mfp_header_after' );
	
	do_action( 'mfp_content_before' );
	echo '<div>CONTENT</div>';
	do_action( 'mfp_content_after' );
	
	do_action( 'mfp_footer_before' );
	echo '<div>FOOTER</div>';
	do_action( 'mfp_footer_after' );

?>

ADD_ACTION

You can add action in the plugin without change index.php in the theme. For example :

<?php
	function mfp_example_header_before1() {
		echo '<div>HEADER BEFORE 1</div>';
	}
	add_action( 'mfp_header_before','mfp_example_header_before1' );
	
	function mfp_example_header_before2() {
		echo '<div>HEADER BEFORE 2</div>';
	}
	add_action( 'mfp_header_before','mfp_example_header_before2' );
	
	function mfp_example_footer_before1() {
		echo '<div>FOOTER BEFORE 1</div>';
	}
	add_action( 'mfp_footer_before','mfp_example_footer_before1' );
?>

REMOVE_ACTION

If you want to remove just use for example remove_action( ‘mfp_header_before’,’mfp_example_header_before2′ ); or if you want to remove all action remove_all_actions( ‘mfp_header_before’ );

WORDPRESS ACTION STANDAR WHICH YOU NEED TO KNOW : wp_head , wp_footer

FILTER

Filter is hook for variable. Function which you need to know apply_filters and add_filter.
Example :

<?php
	function mfp_do_filter( $mfp_text ) {
		$mfp_text = "VAR DO FILTER";
		return $mfp_text;
	}
	add_filter( 'mfp_var_filter', 'mfp_do_filter' );
	
	function mfp_apply_filter() {
		$mfp_var = "VAR APPLY FILTER";
		$mfp_var = apply_filters( 'mfp_var_filter' , $mfp_var );
		echo $mfp_var;
	}
	
	mfp_apply_filter();
?>

REMOVE_FILTER

If you want to remove filter. Just use for example remove_filter( ‘mfp_var_filter’ , ‘mfp_do_filter’ ); or if you want ro remove all just use function remove_all_filter( ‘mfp_var_filter’ );

WORDPRESS FILTER WHICH YOU NEED TO KNOW : the_content

After you know some basic functions now it’s time to create your first plugin.
HERE IS SAMPLE FIRST PLUGIN TO INSERT BEFORE AND AFTER CONTENT IN THE POST / PAGE

<?php
/*
Plugin Name: My First Plugin
Plugin URI: http://wpamanuke.com/how-to-create-wordpress-plugin/
Description: First plugin which i made
Version: 1.0
Author: WPAmanuke
Author URI: http://wpamanuke.com
License: GPLv2
*/

function mfp_filter_the_content_before( $content ) {
    $custom_content = '<div>Before Content Filter</div>';
    $custom_content .= $content;
    return $custom_content;
}
add_filter( 'the_content', 'mfp_filter_the_content_before' );

function mfp_filter_the_content_after( $content ) {
    $custom_content = '<div>After Content Filter</div>';
    $custom_content = $content . $custom_content;
    return $custom_content;
}
add_filter( 'the_content', 'mfp_filter_the_content_after' );

?>