showing wordpress featured image in slider - wordpress

Question

I want show featured image in my slider. so what i've done in my function.php is like below:
<?php
function revconcept_get_images($post_id) {
global $post;
$thumbnail_ID = get_post_thumbnail_id();
$images = get_children( array('post_parent' => $post_id, 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => 'ASC', 'orderby' => 'menu_order ID') );
if ($images) :
foreach ($images as $attachment_id => $image) :
$img_alt = get_post_meta($attachment_id, '_wp_attachment_image_alt', true); //alt
if ($img_alt == '') : $img_alt = $image->post_title; endif;
$big_array = image_downsize( $image->ID, 'large' );
$img_url = $big_array[0];
echo '<li>';
echo '<img src="';
echo $img_url;
echo '" alt="';
echo $img_alt;
echo '" />';
echo '</li><!--end slide-->';
endforeach; endif; }
?>
<div class="flexslider"> <!-- function called in index.php -->
<ul class="slides">
<?php revconcept_get_images("$post->ID"); ?>
</ul>
</div><!--end flexslider-->
Now i have two problem. no.1 My featured image is not showing in the slider. It's showing a broken link. but it can echo the post_id. no.2 I want show only 3/4 images from the latest post of cat=5. can anyone help me to do this ? note that i am using flexslider for my slider.

Answer 1

Ok, this is what I've tested, you may want to refine the query a bit, but for me it worked. In functions.php put
function revconcept_get_images($post_id) {
$images = get_posts( array(
'post_type' => 'attachment',
'hide_empty' => true,
'order' => 'ASC',
'orderby' => 'menu_order ID'
));
foreach ($images as $image) {
$image_url = $image->guid;
$img_alt = get_post_meta($image->ID, '_wp_attachment_image_alt', true); //alt
echo '<li><img src="'.$image_url.'" alt="'.$img_alt.'" /></li>';
}
}
And in index.php put (where you want)
<div class="flexslider"> <!-- function called in index.php -->
<ul class="slides">
<?php revconcept_get_images($post->ID); ?>
</ul>
</div><!--end flexslider-->
If you want to show all featured images from posts you have just put 'posts_per_page' => -1, in the get_posts() array.