C / C++ / MFC

21-Oct-07 22:35

Hello everyone,

I saw a couple of form of assert in code on Windows,

1. ASSERT;
2. assert;
3. _ASSERT;
4. _assert.

Which one is the most correct to use? I saw people always define this to that, and I want to find the root one which is defined by Windows.

I also saw people manually define assert to NULL if macro DEBUG or _DEBUG is not defined, is that necessary?

I feel assert is in a mess and I want to find a clear and unified way for this item.

thanks in advance,
George

Matthew Faithfull21-Oct-07 23:08

Matthew Faithfull

21-Oct-07 23:08

Yes assert is a bit of a mess. One of the reasons for this is that it isn't defined by Windows. It is defined by the C Library but not in a particularly good, reusable or modifyable way. Hence every library writer tends to create their own so now we have several less than ideal assert macros and functions. In the end the choice comes down to: use the one that suits you best, none is really more or less correct, or do what every one else has done and write your own Smile | :)

The third way I suppose is to find another implementation you like and copy it. John Robbin's SuperAssert is certainly the most complete I've come across.

Nothing is exactly what it seems but everything with seems can be unpicked.

George_George22-Oct-07 0:10

22-Oct-07 0:10

Thanks Matthew,

After reading MSDN,

http://msdn2.microsoft.com/en-us/library/9sb57dw4(VS.71).aspx
http://msdn2.microsoft.com/en-us/library/ezb1wyez(VS.71).aspx[^]

1. I think we need to use _ASSERT for bool expression;
2. we need to use assert for int expression;
3. No need to define _ASSERT and assert to NULL manually when _DEBUG is not defined.

Right?

regards,
George

Matthew Faithfull22-Oct-07 0:46

Matthew Faithfull

22-Oct-07 0:46

The link doesn't work for me but that sounds OK. assert will be taking an int because it's in 'C' where bool doesn't exist. I would say if you're going to use the existing asserts then use the MFC version with MFC and the C Library version in plain Win32. There is certainly no need define _ASSERT and assert manually to NULL when !_DEBUG. They should already be #defin(ed) to disappear altogether in Release builds.
I understand the value of asserts but I don't personally use them. I know this is a controversial oppinion and not to be taken as advice but I think they're an incomplete or broken concept. One of these days I'm going to work out why they annoy me so much and replace them with something better. Smile | :)

Nothing is exactly what it seems but everything with seems can be unpicked.

George_George22-Oct-07 1:52

22-Oct-07 1:52

Thanks for sharing your experience, Matthew!

regards,
George

Stephen Hewitt22-Oct-07 15:36

Stephen Hewitt

22-Oct-07 15:36

Matthew Faithfull wrote:
or do what every one else has done and write your own

Just what we need, another bloody assert macro!

Steve

David Crow22-Oct-07 3:45

David Crow

22-Oct-07 3:45

George_George wrote:
1. ASSERT;
2. assert;
3. _ASSERT;
4. _assert.

Which one is the most correct to use?

I use #1 for MFC, and #2 for Win32. If you are curious what each resolves to, if anything, just place the mouse cursor on it and press F12.

"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

George_George22-Oct-07 19:26

22-Oct-07 19:26

Thanks DavidCrow,

I think there is no need to manually define ASSERT and other forms of ASSERT to NULL when in release configuration, right?

regards,
George

David Crow23-Oct-07 2:55

David Crow

23-Oct-07 2:55

George_George wrote:
I think there is no need to manually define ASSERT and other forms of ASSERT to NULL when in release configuration, right?

I've never had the need to, but then again, I'm prejudice.

George_George23-Oct-07 4:41

23-Oct-07 4:41

Hi DavidCrow,

I agree.

regards,
George

James R. Twine22-Oct-07 5:18

James R. Twine

22-Oct-07 5:18

If in the VS environment, I vote for _ASSERTE(...) because it echos the failed expression in the assert dialog that pops up - much easier to see if you should skip it (i.e. a known problem) or actually investigate.

The non-Debug #defines for assert-related macros are usually to allow release-build code to work correctly if the macro includes a statement terminator. For example, if you have the following code:

if( test != value )
    MyMagicAssert( test )

The above code might be correct if the MyMagicAssert macro contains a semicolon or expands to something that is scoped by { and }.

If in a release build MyMagicAssert was #defineed to nothing, the code would evaluate to become:

if( test != value )
    // Nothing Here

So without scope or a semicolon, the if(...) would associate to the next line of code, which would likely be an accident. By #defineing the macro to a semicolon or to {} the code compiles and runs as expected.

Peace!

-=- James
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George_George22-Oct-07 18:58

How to get text from Form?

22-Oct-07 18:58

Hi James,

I agree and learn all from your reply, except this point. I think we do not need to manually define _ASSERT to NULL is _DEBUG or not defined, right?

regards,
George

truestepper21-Oct-07 22:20

truestepper

21-Oct-07 22:20

There are some forms in which enumchildwindows doesn't return child elements, while on the screen I can see statics, labels... for Example in Office word 2003 Tools->Options (You can try with spy++) How to capture this text?

Hamid_RT21-Oct-07 22:28

Hamid_RT

21-Oct-07 22:28

Do you want to get text of controls on your program or other programs?

truestepper21-Oct-07 22:30

truestepper

21-Oct-07 22:30

From other program.

Hamid_RT21-Oct-07 22:41

Hamid_RT

21-Oct-07 22:41

For get or set text you need to handle(hwnd) do you have any CWnd of that window if you have you can use of this code if you run this code on your program it change text of all controls to 123 and vice versa for get text of control (if you have code can you show it dont need to post all code)

for(CWnd* pWnd = GetTopWindow(); pWnd;pWnd = pWnd ->GetNextWindow())
	{
	pWnd ->SetWindowTextW(_T("123"));
	}

truestepper21-Oct-07 22:47

truestepper

21-Oct-07 22:47

I have only hwnd of main window, and enumchildwindows doesn't return any child windows, but I can see them on form. Please read my first post carefully.