The cci_col_set_add function adds a member to the set attribute values. The following example shows how to add "a" to the set attribute values.
cci_col_set_add(con_id, oid_str, set_attr, "a", err_buf);
intcci_col_set_add ( int conn_handle, char *oid_str, char *col_attr, char *value, T_CCI_ERRROR *err_buf)