How to print the src attribute of an ImageElement

Hi,

Can you please tell me how call I print out the src attribute of an
ImageElement to the screen?
I have the following code, but I only see 1 character 'h'.

nsCOMPtr<nsIDOMHTMLImageElement> img;

      if (img) {
        printf ( "img element is not null");

           nsAutoString srcAttr;

           img->GetAttribute(NS_LITERAL_STRING("src"), srcAttr);

           if (!srcAttr.IsEmpty()) {
             printf("%s", srcAttr.get());
           }
      }

Thank you for any help.