Custom Taxonomy List links being re-written

Question

I am trying to show a list of terms from my Job Category. I tried the following:

function job_listing_taxonomy_list( $taxonomy,$hide ) {
    $args = array('order'=>'ASC','hide_empty'=>$hide);
    $terms = get_terms( $taxonomy, $args );
    if ( $terms ) {
        printf( '<ul name="%s">', esc_attr( $taxonomy ) );
        foreach ( $terms as $term ) {
            printf( '<li><a href="http://example.com/?s=&'.$taxonomy.'=%s">%s</a></li>', esc_attr( $term->slug ), esc_html( $term->name ) );
        }
        print( '</ul>' );
    }
}

However, when I click the link of one of the terms that are generated, for example:

http://example.com/?s=&job_listing_category=finance

it is changed to:

http://example.com/?s?job_listing_category=finance

Why is the =& changing to a '?' ? I've spent a good half an hour combing Google and this site for answers, but I'm not entirely sure what to even look for! On a side note, I did have a Custom Post Type Permalink Rewrite plugin installed earlier which caused a Strict Standards error, but after disabling it (turns out I wasn't using it anyway), I now get this error....

Any suggestions?

Edit: I've tried replacing the & with &, but it didn't make a difference

Answer 1

After taking @Milo 's comments into consideration, I removed the s= argument from the link, and it worked!

This is my final code:

function job_listing_taxonomy_list( $taxonomy,$hide ) {
    $args = array('order'=>'ASC','hide_empty'=>$hide);
    $terms = get_terms( $taxonomy, $args );
    if ( $terms ) {
        printf( '<ul name="%s">', esc_attr( $taxonomy ) );
        foreach ( $terms as $term ) {
            printf( '<li><a href="%s/?'.$taxonomy.'=%s">%s</a></li>', site_url() ,esc_attr( $term->slug ), esc_html( $term->name ) );
        }
        print( '</ul>' );
    }
}

The difference is that I removed the s= argument, and added site_url() as well so that I don't have to change it when the site is moved to the live server.

The only reason I had the s= there in the first place, was because I was adapting the search URL from my search bar, and so in my lack of understanding I assumed that it needed the s= there in order to function. Evidently not!