I recently had to make a theme that used similar code on different custom post types. For this I want to do something different depending on the post type. To get the post type for the current post Wordpress has a built in function that allows you to do this easily. If you are inside the loop of a single post then you can just use the function get_post_type().
echo get_post_type( $post_id );
This function has 1 argument which is optional, this is the post ID. If you don't pass a argument into the function then it will use the global $post variable which is set inside the loop. get_post_type returns a string of the post type of the post ID or the current post, from this value you can do a check on the post type to decide what you do with it, like the code below.
$post_type = get_post_type();
switch( $post_type )
{
case 'task':
// do code for task post type
break;
case 'todo':
// do code for task post type
break;
}
Now I can use this code in a common file used across multiple post types and do different things depending on the post type.