Page 44 - DCAP408_WEB_PROGRAMMING

Windows Programming

Notes __in WPARAM wParam,
__in LPARAM lParam
);
Parameters

hwnd [in]

Type: HWND
A handle to the window.
uMsg [in]
Type: UINT
The message.

For lists of the system-provided messages, see System-Defined Messages.
wParam [in]
Type: WPARAM

Additional message information. The contents of this parameter depend on the value of
the uMsg parameter.
lParam [in]

Type: LPARAM
Additional message information. The contents of this parameter depend on the value of
the uMsg parameter.

Return value

Type: LRESULT

The return value is the result of the message processing and depends on the message sent.
If your application runs on a 32-bit version of Windows operating system, uncaught exceptions
from the callback will be passed onto higher-level exception handlers of your application when
available. The system then calls the unhandled exception filter to handle the exception prior to
terminating the process. If the PCA is enabled, it will offer to fix the problem the next time you
run the application.
However, if your application runs on a 64-bit version of Windows operating system or WOW64,
you should be aware that a 64-bit operating system handles uncaught exceptions differently
based on its 64-bit processor architecture, exception architecture, and calling convention. The
following table summarizes all possible ways that a 64-bit Windows operating system or WOW64
handles uncaught exceptions.
Behavior type How the system handles uncaught exceptions
1 The system suppresses any uncaught exceptions.
2 The system first terminates the process, and then the Program Compatibility
Assistant (PCA) offers to fix it the next time you run the application. You can disable
the PCA mitigation by adding a Compatibility section to the application manifest.
3 The system calls the exception filters but suppresses any uncaught exceptions when
it leaves the callback scope, without invoking the associated handlers.

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