FIX: CommitQQ Does Not Flush Buffers

The information in this article applies to:

• Microsoft FORTRAN PowerStation for MS-DOS versions 1.0 and 1.0a

SYMPTOMS

Calling CommitQQ after writing data will not force the data to be written to the physical device. Any data in the buffer that was not already written to the device will remain in the buffer.

RESOLUTION

The only way to flush the write buffer is to close the I/O unit and then re-open it. For sequential files the status should be "APPEND" when re-opening.

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. This problem was fixed in Fortran PowerStation 32 for Windows NT, version 1.0.

MORE INFORMATION

The problem can be demonstrated as follows:

1. Build the sample program TCOMMIT.FOR in the \F32\SAMPLES\RUNTIME directory, and run the executable from Windows.

2. Type in some text when asked. When the program displays "If you boot now, your text will be saved," go to File Manager.

3. In File Manager, display the directory \F32\SAMPLES\RUNTIME with full file details.

4. Press the <F5> key to refresh (ensuring that the latest information about the files is being displayed).

5. Check the size of 'COMMITQQ.TST.'

6. The size of 'COMMITQQ.TST' will still be zero indicating that the write buffers were not flushed despite calling the CommitQQ function. Go back to the TCOMMIT program, and press the <Enter> key twice to exit.

7. Repeat steps 3, 4, and 5. The size of 'COMMITQQ.TST' will no longer be zero. This indicates that the write buffers were flushed only when the file unit was closed on program termination.