mfc debugging
in [MFC]
|
From: rahul on 21 Jan 2010 01:59 Sometimes in WATCH window of VS.NET (MFC) value of object is dispalyed 0x00000081 {unused=???} What is the meaning of "{unused=???}" in watch window. Also what is the meaning of CX0030 error:(expression can not be evaluated)
From: Stephen Myers on 21 Jan 2010 11:45 rahul wrote: > Sometimes in WATCH window of VS.NET (MFC) value of object is dispalyed > 0x00000081 {unused=???} > What is the meaning of "{unused=???}" in watch window. > Also what is the meaning of CX0030 error:(expression can not be > evaluated) Low values like 0x00000081 are generally the result of the IDE trying to understand an object based on a null pointer. This causes all kinds of problems when the IDE tries to display information. Check that the base address for the object is not NULL. Steve
From: Drew on 21 Jan 2010 11:50 "rahul" <hyrahul64(a)gmail.com> wrote in message news:d2546bfd-1a59-47ed-b80d-39953946c507(a)e37g2000yqn.googlegroups.com... > Sometimes in WATCH window of VS.NET (MFC) value of object is dispalyed > 0x00000081 {unused=???} What object? What version of VS? What OS? > What is the meaning of "{unused=???}" in watch window. > Also what is the meaning of CX0030 error:(expression can not be > evaluated) The meaning is self explanatory. Is this expression a static? No information can be provided without further context. It looks like some offset of a NULL pointer. Show some code. Drew
From: Joseph M. Newcomer on 21 Jan 2010 12:22 Since you did not mention the type of the object, it is hard to give you a good explanation. However, it is most likely it is a HANDLE type of some sort. Examining the definition of a handle, we find that #define DECLARE_HANDLE(name) struct name##__ { int unused; }; typedef struct name##__ *name so that would explain the "unused" name. CX0030 means that you have an expression that evaluates to an illegal address, or involves a reference to an illegal address. For example WHATEVER * p; If you look at p in the debugger, if p is a valid pointer, it will show you what it points to; you can expand the structure, for example. If p is NULL, or 0xCCCCCCCC [an uninitialized local in debug mode], 0xDFDFDFDF [an uninitialized heap value in debug mode], or 0xFEEEFEEE [a pointer found in a structure that has been freed] then you are told it is an expression which cannot be evaluated. joe On Wed, 20 Jan 2010 22:59:24 -0800 (PST), rahul <hyrahul64(a)gmail.com> wrote: >Sometimes in WATCH window of VS.NET (MFC) value of object is dispalyed >0x00000081 {unused=???} >What is the meaning of "{unused=???}" in watch window. >Also what is the meaning of CX0030 error:(expression can not be >evaluated) Joseph M. Newcomer [MVP] email: newcomer(a)flounder.com Web: http://www.flounder.com MVP Tips: http://www.flounder.com/mvp_tips.htm
|
Pages: 1 Prev: use "template" in C Next: How to find if a path is network or local |