PRB: Print Break in MFC App Running in Windows NT 3.51 Checked

ID: Q138993

The information in this article applies to:

The Microsoft Foundation Classes (MFC), included with:
- Microsoft Visual C++ 32-bit Edition, versions 2.0, 2.1, 2.2, 4.0

SYMPTOMS

While using the Visual C++ debugger, if you click Print or Print Preview in an MFC application running under Windows NT version 3.51 Checked Build, a message box appears:

In the Visual C++ 2.x debugger, the message box contains:

Break caused by hard coded breakpoint instruction

In the Visual C++ 4.0 debugger, the message box contains:

User breakpoint called from code at 0x<8-digit address>

The following message is also printed in the Output Window of the debugger:

BASE: GlobalFree called with a locked object.

CAUSE

MFC queries an HDEVNAMES handle for information about the printer device. This information is obtained by making calls to GlobalLock to get a valid pointer to the DEVNAMES structure. Under Win32, it is not technically necessary to call GlobalUnlock for every GlobalLock, so MFC doesn't always do so.

The Checked Build of Windows NT 3.51 provides debugging information that warns you when GlobalFree is called on an object that does not have a lock count of 0. When this occurs, it outputs a trace message and causes a hard coded break instruction to be executed.

RESOLUTION

The message and the break can be safely ignored. To continue with execution in the debugger, you can just click Go on the Debug menu, or press the F5 key.

STATUS

This behavior is by design.

Additional query words: 2.00 2.10 2.20 4.00 3.00 3.10 3.20

Keywords : kberrmsg kbMFC kbPrinting kbVC
Version : winnt:
Platform : winnt
Issue type :