$post->post_parent behaves different on page then in functions.php - php

Question

I created/modified a function to display breadcrumbs on pages on WordPress. The modified version makes use of #post->post_parent to get the parent of a page in order to have a full breadcrumb trail (home > page 1 > page 2 > page 3 vs. home > page 3)
The code executes perfectly on page (ie. home > page 1 > page 2 > page 3). But when I place it into a function and call it form the functions.php page it cannot detect if the page has a parent using $post->post_parent (ie. page 3 vs. home > page 3).
Could this be because the on page code is executed in the_loop but the function is somehow outside of it?
On page code:
if (!is_home()) {
echo "<ul id='breadcrumb'>";
echo '<li><a href="';
echo get_option('home');
echo '">HOME';
echo "</a></li>";
if (is_category() || is_single()) {
the_category('title_li=');
if (is_single()) {
the_title('<li>', '</li>');
echo "</ul>";
}
} elseif (is_page()) {
if(!$post->post_parent){
//echo "No Parent";
}
else{
echo '<li>'. wp_list_pages('include='.$post->post_parent.'&title_li=' ).'</li>';
}
the_title('<li>', '</li>');
echo "</ul>";
}
}
Function code:
function the_breadcrumb() {
if (!is_home()) {
echo "<ul id='breadcrumb'>";
echo '<li><a href="';
echo get_option('home');
echo '">HOME';
echo "</a></li>";
if (is_category() || is_single()) {
the_category('title_li=');
if (is_single()) {
the_title('<li>', '</li>');
echo "</ul>";
}
} elseif (is_page()) {
if(!$post->post_parent){
//echo "No Parent";
}
else{
echo '<li>'. wp_list_pages('include='.$post->post_parent.'&title_li=' ).'</li>';
}
the_title('<li>', '</li>');
echo "</ul>";
}
}
}
There is nothing inherently different about this code except that it is now wrapped in a function. The fact that it doesn't display the parent pages is frustrating. I don't want to have to include this code on every page template I create.
Help & Suggestions will be greatly appreciated!

Answer 1

$post ist not defined in your function. Try to give $post as parameter to the function:
function the_breadcrumb($post) {

Answer 2

Or, define
global $post;
at the top of the function.
function fname()
{
global $post;
code...
}