public Int32 HNC_ParamanGetFileName(Int32 fileNo, ref String buf)
{
Int32 ret = -1;
IntPtr ptr = Marshal.AllocHGlobal(HNCDATADEF.PARAMAN_LIB_TITLE_SIZE);
ret = HncApi.HNC_ParamanGetFileName(fileNo, ptr, _ClientNo);
buf = Marshal.PtrToStringAnsi(ptr);
Marshal.FreeHGlobal(ptr);
return(ret);
}