How to make this function effective "dwg_ent_attrib_set_text"

[fly-sure]

I want to modify the text of the attribute value. I called the function dwg_ent_attrib_set_text, but the dwg file did not change. Is it because I am using it incorrectly or am I missing some necessary code?

  success = dwg_read_file (filename, &dwg);
  
    for (i = 0; i < dwg.num_objects; i++)
    {
      if (dwg.object[i].fixedtype == DWG_TYPE_ATTRIB)
        {
          Dwg_Entity_ATTRIB *_obj = dwg.object[i].tio.entity->tio.ATTRIB; 
          dwg_ent_attrib_set_text(_obj,"hello",0);
        }
    }