Code-Snippets-Functions/Execute a function on a child site/WooCommerce/change-product-price-zero-as-free.txt

// Cart and minicart
add_filter( 'woocommerce_cart_item_price', 'change_cart_item_price_html', 10, 3 );
function change_cart_item_price_html( $price_html, $cart_item, $cart_item_key ) {
    if( $cart_item['data']->get_price() == 0 ) {
        return '<span class="woocommerce-Price-amount amount">'.__("FREE", "woocommerce").'</span>';
    }
    return $price_html;
}

// Cart and Checkout
add_filter( 'woocommerce_cart_item_subtotal', 'change_checkout_item_subtotal_html', 10, 3 );
function change_checkout_item_subtotal_html( $subtotal_html, $cart_item, $cart_item_key ) {
    if( $cart_item['data']->get_price() == 0 ) {
        return '<span class="woocommerce-Price-amount amount">'.__("FREE", "woocommerce").'</span>';
    }
    return $subtotal_html;
}