Wordpress: Notice:Object of class WP_Query could not be converted to int in on line

Question

I am facing issue in debug mode with wordpress. In my featured slider getting error Notice: Object of class WP_Query could not be converted to int in on line

I am using below code for my slider

<div id="<?php slider_class() //Theme function ?>" class="clearfix">

    <!--[BEGIN: Slider wrapper]-->
    <div id="slides-wrapper" <?php slider_wrapper_class() //Theme function ?>>
        <!--[BEGIN: #Slides]-->
        <div id="slides" class="<?php slides_class() //Theme function ?> clearfix">
            <!--[BEGIN: Slides_container]-->
            <div class="slides_container <?php slides_class() //Theme function ?>">

                <?php
                $featuredPosts = new WP_Query();
                $featuredPosts->query('showposts='.get_option('mp_slides_no').'&category_name='.get_option('mp_featured_cat').'');

                for($i=1; $i<=$featuredPosts; $i++) { // second for() loop for post slides
                while ($featuredPosts->have_posts()) : $featuredPosts->the_post(); // loop for posts
                ?>

                <?php if (get_option('mp_slides_content') === "content_s") { ?>
                <!--[BEGIN: ALL SLIDES ++]-->
                <div class="slide clearfix">
                    <!-- thumbnail start -->
                    <?php mp_thumb('featured-thumbnail','featured-slider-thumbnail','480'); //Theme function  ?>
                    <!-- end of thumbnail -->

                    <div class="featured-excerpt">
                        <h2 class="title"><a href="<?php the_permalink(); ?>"><?php echo substr($post->post_title,0,50); // short title ?>...</a></h2>

                        <?php the_excerpt(); ?>
                        <br />
                        <a href="<?php the_permalink(); ?>" class="featured-readmore clearfix"><span>Read more</span><img src="<?php bloginfo('template_directory'); ?>/images/button-arrow.png" alt="readmore" width="24" height="24" /></a>
                    </div>

                </div>
                <!--[END: ALL SLIDES ++]-->

                <?php } elseif (get_option('mp_slides_content') === "image_s") { ?>

                <!--[image slider start]-->

                <!--[BEGIN: ALL SLIDES ++]-->
                <div class="slide clearfix">
                    <!-- thumbnail start -->
                    <?php if (get_option('mp_slides_style') === "fixed") { ?>

                        <?php mp_thumb('featured-thumbnail','featured-slider-image920','920'); //Theme function  ?>

                    <?php } else { ?>

                        <?php mp_thumb('featured-thumbnail','featured-slider-image960','960'); //Theme function  ?>

                    <?php } ?>
                    <!-- end of thumbnail -->

                </div>
                <!--[END: ALL SLIDES ++]-->             

                <!--[end of image slider]-->

                <?php } ?>

                <?php endwhile;
                } // end for() loop number 2
                ?>

            </div>
            <!--[END: Slides_container]-->

            <a href="#" class="prev"></a>
            <a href="#" class="next"></a>

        </div>
        <!--[END: #Slides]-->

    </div>
    <!--[END: Slider wrapper]-->

</div>

//theme function are nothing but switching the class for style

--[ Resolved Code ]------------------------------------------------------------------- As I am new to php I didn't realized I am using two loop at the same time for and while. With Manny Fleurmond's comment my mind just clicked and I use below code and it just works fine with me. Also changed post_per_page option as m0r7if3r said. Please tell me if anything is wrong in this code.

$temp = $wp_query;
                $wp_query = null;
                $wp_query = new WP_Query();
                $wp_query->query('category_name='.get_option('mp_featured_cat').'&posts_per_page='.get_option('mp_slides_no').'');          

                while ( $wp_query->have_posts() ) : $wp_query->the_post(); // loop for posts
                ?>

Answer 1

Your problem is here:

$featuredPosts = new WP_Query();
$featuredPosts->query('showposts='.get_option('mp_slides_no').'&category_name='.get_option('mp_featured_cat').'');

for($i=1; $i<=$featuredPosts; $i++) {

You're creating a new instance of WP_Query to run a custom query and storing it in the $featuredPosts variable. But then you're trying to use $featuredPosts as the upper limit of a for loop. This is what PHP is complaining about. Your $i<=$featuredPosts should be something more like $i<=count($featuredPosts->posts).

That said, you're using actual Loop functions below that ... which belong in a while($featuredPosts->have_posts()) loop instead of a regular for loop ...

Answer 2

Try changing this:

<?php
$featuredPosts = new WP_Query();
$featuredPosts->query('showposts='.get_option('mp_slides_no').'&category_name='.get_option('mp_featured_cat').'');

...to this:

<?php
$featuredPosts_args = array(
    'showposts' => get_option( 'mp_slides_no' ),
    'category_name' => get_option('mp_featured_cat')
);
$featuredPosts = new WP_Query( $featuredPosts_args );
?>

Ultimately, I think this is your problem:

for($i=1; $i<=$featuredPosts; $i++)

Here, $featuredPosts is an object, not an integer. Either find another way to do what you're trying to do here, or get rid of this for loop entirely.