Microsoft KB Archive/43530

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Article ID: 43530

Article Last Modified on 11/21/2006

This article was previously published under Q43530


Choosing to UNLOAD a file while a Watch on a variable is set hangs the QB.EXE editor, requiring a warm or cold reboot if operating under MS-DOS. If you are running under OS/2, this choice hangs the DOS compatibility box. This problem does not occur when UNLOADing a file if a Watchpoint is set to watch an expression.


Microsoft has confirmed this to be a bug with QB.EXE in QuickBasic version 4.50. This problem was corrected in QBX.EXE in Microsoft Basic Professional Development System (PDS) version 7.00 (fixlist7.00).


Example 1

To demonstrate this problem do the following:

  1. Type the following two lines in the QuickBasic editor:

    B$ = "Hello"

  2. Save the file by choosing Save As from the File menu.
  3. Choose Add Watch from the Debug menu by pressing ALT+D and then pressing "A".
  4. Enter B$ as the expression to watch. Press ENTER.
  5. Choose Unload from the File menu by pressing ALT+F and then pressing "U". Press ENTER to UNLOAD the program. The editor will then display a menu prompting you to choose a new main module. If the editor does not hang, press ENTER again to choose "Untitled" as the main module. At this point the editor will hang, requiring a cold or warm reboot.

Example 2

The following exact steps also cause QB.EXE version 4.50 to hang under similar circumstances:

  1. Start QuickBasic and load any Quick library:

    QB /L QB.QLB

  2. Type the following and press ENTER:

    PRINT "any text"

  3. Press the UP ARROW cursor key, thus placing the cursor under the "P" in PRINT.
  4. Press F9, thus placing a breakpoint on that line.
  5. Run the program by pressing SHIFT+F5.
  6. Select the Debug menu with ALT+D and press ENTER, thus choosing to set a watch variable.
  7. Type FRE("") as the watch variable and press ENTER.
  8. Press ALT+F+L (to select the Load File command), and press ESC.
  9. Press ALT+F+U (to select the Unload File command), and press ENTER.
  10. Press TAB, then the SPACE key, then ENTER, and the editor will be hung.

Additional query words: QuickBas BasicCom SR# S890410-127 buglist4.50 B_BasicCom

Keywords: KB43530