windows 的磁盘清除，怎么跳过扇区（或者字节来写入），以下代码怎么改

LPCTSTR str = wth;//\\.\PHYSICALDRIVE1

HANDLE hDevice=CreateFile(str,GENERIC_READ | GENERIC_WRITE,FILE_SHARE_READ|FILE_SHARE_WRITE,NULL,OPEN_EXISTING,0,NULL);
if(hDevice==INVALID_HANDLE_VALUE)
{
    printf("read disk error!\n");
}
DISK_GEOMETRY DiskGeom1;DWORD return_bytes;
if(!DeviceIoControl(hDevice,IOCTL_DISK_GET_DRIVE_GEOMETRY,NULL,0,&DiskGeom1,sizeof(DISK_GEOMETRY),&return_bytes,NULL))
{
    printf("DeviceIoControl error!\n");
    //int ret = GetLastError();
    CloseHandle(hDevice);
    CloseHandle(hDevice);
}
unsigned long writed = 0;
for(int i=0;i<1024;i++)
{
    int  ret =0;
    ret= WriteFile(hDevice,ch,1024*1024,&writed,NULL);
    if(ret>0)
    {
           printf("write disk now!\n");
           printf("ret=%d\n",ret);
    }
    else
        printf("write disk error!\n");
}
FlushFileBuffers(hDevice);
CloseHandle(hDevice);