/*
 * call-seq:
 *    res.fieldname( index )
 *
 * Returns the name of the field (column) corresponding to the index.
 *
 *   res=conn.exec("SELECT foo,bar AS biggles,jim,jam FROM mytable")
 *   puts res.fieldname(2) => 'jim'
 *   puts res.fieldname(1) => 'biggles'
 *
 * Equivalent to <tt>res.fields[_index_]</tt>.
 */
static VALUE
pgresult_fieldname(obj, index)
    VALUE obj, index;
{
    PGresult *result;
    int i = NUM2INT(index);
    char *name;

    result = get_pgresult(obj);
    if (i < 0 || i >= PQnfields(result)) {
        rb_raise(rb_eArgError,"invalid field number %d", i);
    }
    name = PQfname(result, i);
    return rb_tainted_str_new2(name);
}