Question

I have built a very simple plugin and uploaded it on my wordpress account which is run on localhost. Once I activate it, its output will be shown on every page, and it wont be added to the left hand side menu of wordpress. what should I add to it to be added to the menu? I suppose it should be done using add_action but do not know how !!

<?php
/*
Plugin Name: myphotos Plugin
Description: A simple wordpress plugin.
Version: 1.0
Author: Saeed Pirdost
Copyright: 2012,  Saeed Pirdost
*/
?>
<?php 
add_filter('admin_notices','myprint');
?>
function myprint()
{
    echo "hello";
}
?>

I used the following code as well but when I activate the plugin just a white page will be shown.

add_menu_page(__('My Menu Page'), __('My Menu'), 'edit_themes', 'my_new_menu', 'myprint', '', 7); 

Answer 1

First, stop opening and closing PHP tags at every line, you don’t need that. This is used when some HTML is happening in the middle of your PHP.

Also, the last closing ?> of a PHP file can/should be omitted. It may even break a site if there is a white-space after it…

Refer to WordPress_Coding_Standards.

---

Second, you need to decide if you want to use the function my_print as callback of admin_notices or of add_menu_page. Can it be both? In this case, yes, but really, do it only if you know what you are doing.

---

Your plugin is breaking because add_menu_page cannot be called directly.
Always check the documentation of each function that don’t work as expected:
Function_Reference/add_menu_page

---

Here’s a working version of your plugin:

<?php
/*
Plugin Name: myphotos Plugin
Description: A simple wordpress plugin.
Version: 1.0
Author: Saeed Pirdost
Copyright: 2012,  Saeed Pirdost
*/

add_filter( 'admin_notices', 'print_my_notice' );

add_action( 'admin_menu', 'register_custom_menu_page' );

function print_my_notice()
{
    echo '<div class="updated">
           <p>I am a big notice that appears everywhere</p>
        </div>';
}

function register_custom_menu_page() 
{
    add_menu_page(
        __( 'My Menu Page', 'my-plugin-text-domain' ), 
        __( 'My Menu', 'my-plugin-text-domain' ), 
        'edit_themes', 
        'my_new_menu', 
        'print_my_menu', 
        'http://upload.wikimedia.org/wikipedia/commons/a/aa/Wink%2816px%29.svg', 
        7
    );      
}

function print_my_menu()
{
    echo '<div id="icon-post" class="icon32"></div>
        <h2>My plugin</h2>
            <p><a class="button-secondary" href="#"> ' 
            . __( 'I am a translation', 'my-plugin-text-domain' ) 
            . '</a>
            </p>';
}