Theme Category is being displayed as a List

simple_portfolio_list_categories($post_id = null, $args = null)

this is a custom function of your theme, and looks more like it is supposed to show the list of all blog categories (analogue to ‘wp_list_categories()’ ).

the ‘normal’ wordpress function to show the post categories would be the_category(); –
however in your case you need to get the categories as a string to use in the printf() function,
and you could use:

get_the_category_list( ', ' )

https://phpxref.ftwr.co.uk/wordpress/nav.html?wp-includes/category-template.php.html#get_the_category_list

thanks! You are right. I was using the wrong function. I come across another problem though. The value that its returning is ‘Array’.

I’ve changed the code below to make it simpler. What do you guys think?

code:
posted in <?php echo simple_portfolio_get_categories( ', ' ); ?> on <?php echo get_the_date(); ?>

output:
posted in Array on October 17, 2010

why don’t you use:

<?php echo get_the_category_list( ', ' ); ?>

which would output a linked list of the post’s categories.

simple_portfolio_get_categories( ', ' ); seems to return an array of categories, which would need a different output method.

It’s not returning anything. ??

You can check the plugin:
https://www.ads-software.com/extend/plugins/simple-portfolio/

The developer also provided a theme to go with it:
https://projects.inlet.nl/simple-portfolio-wordpress3/wp-content/uploads/2010/07/simple-portfolio-theme.zip

Even with this theme, the get_categories function won’t work. ??