Formats a specified, contiguous set of tracks on a floppy disk. To provide additional parameters, use IOCTL_DISK_FORMAT_TRACKS_EX instead.

To perform this operation, call the DeviceIoControl function with the following parameters.

BOOL DeviceIoControl(
  (HANDLE) hDevice,            // handle to device
  IOCTL_DISK_FORMAT_TRACKS,    // dwIoControlCode
  (LPVOID) lpInBuffer,         // input buffer 
  (DWORD) nInBufferSize,       // size of input buffer 
  (LPVOID) lpOutBuffer,        // output buffer
  (DWORD) nOutBufferSize,      // size of output buffer
  (LPDWORD) lpBytesReturned,   // number of bytes returned
  (LPOVERLAPPED) lpOverlapped  // OVERLAPPED structure



A handle to the floppy disk to be formatted. To retrieve a device handle, call the CreateFile function.


The control code for the operation. Use IOCTL_DISK_FORMAT_TRACKS for this operation.


A pointer to a buffer that contains a FORMAT_PARAMETERS data structure.


The size of the input buffer, in bytes.


A pointer to a buffer that receives a variable number of elements of the BAD_TRACK_NUMBER type. Each element contains the track number of one bad disk track.


The size of the output buffer, in bytes.


A pointer to a variable that receives the size of the data stored in the output buffer, in bytes.

If the output buffer is too small to receive any data, the call fails, GetLastError returns ERROR_INSUFFICIENT_BUFFER, and lpBytesReturned is zero.

If the output buffer is too small to hold all of the data but can hold some entries, some drivers will return as much data as fits. In this case, the call fails, GetLastError returns ERROR_MORE_DATA, and lpBytesReturned indicates the amount of data received. Your application should call DeviceIoControl again with the same operation, specifying a new starting point.

If lpOverlapped is NULL, lpBytesReturned cannot be NULL. Even when an operation returns no output data and lpOutBuffer is NULL, DeviceIoControl makes use of lpBytesReturned. After such an operation, the value of lpBytesReturned is meaningless.

If lpOverlapped is not NULL, lpBytesReturned can be NULL. If this parameter is not NULL and the operation returns data, lpBytesReturned is meaningless until the overlapped operation has completed. To retrieve the number of bytes returned, call GetOverlappedResult. If hDevice is associated with an I/O completion port, you can retrieve the number of bytes returned by calling GetQueuedCompletionStatus.


A pointer to an OVERLAPPED structure.

If hDevice was opened without specifying FILE_FLAG_OVERLAPPED, lpOverlapped is ignored.

If hDevice was opened with the FILE_FLAG_OVERLAPPED flag, the operation is performed as an overlapped (asynchronous) operation. In this case, lpOverlapped must point to a valid OVERLAPPED structure that contains a handle to an event object. Otherwise, the function fails in unpredictable ways.

For overlapped operations, DeviceIoControl returns immediately, and the event object is signaled when the operation has been completed. Otherwise, the function does not return until the operation has been completed or an error occurs.

Return value

If the operation completes successfully, DeviceIoControl returns a nonzero value.

If the operation fails or is pending, DeviceIoControl returns zero. To get extended error information, call GetLastError.

It is impossible to determine how many bad track numbers will be returned by this control code, so you should set the size of the array pointed to by the lpOutBuffer parameter to the following:

(total number of tracks on the floppy disk) * sizeof(BAD_TRACK_NUMBER).


Minimum supported client

Windows XP [desktop apps only]

Minimum supported server

Windows Server 2003 [desktop apps only]


WinIoCtl.h (include Windows.h)

See also

Disk Management Control Codes