C / C++ / MFC Discussion Boards

Visual Studio crashed with using java.exe to load DLL

George_George13-Aug-07 20:35

13-Aug-07 20:35

Hello everyone,

I am using Visual Studio 2003. I am writing a JNI program, and upper layer is Java code and lower layer is C code (DLL). The Java code is utilizing C code by JNI.

To debug the C code, in the C DLL Project Properties dialog, I assign Debugging Command to java, then set Command argument to,

-classpath "C:\Program Files\Java\jdk1.5.0_06" HelloWorld,

when when debugging from Visual Studio, Visual Studio will crash. Do you know anything wrong with the settings?

I have also tried to run manually from command line,

java -classpath "C:\Program Files\Java\jdk1.5.0_06" HelloWorld

and the result is correct.

regards,
George

How to handle WM_NCLBUTTONUP in my window.

ss43113-Aug-07 19:13

ss431

13-Aug-07 19:13

hiiii,

I want to handle WM_NCLBUTTONUP in my doc/view application. I already add this message handler for my window. But it was not responded when my mouse was up in the caption bar of my window.Please give suggestion for how to handle the WM_NCLBUTTONUP?

Thanks in advance...

ss

Re: How to handle WM_NCLBUTTONUP in my window.

Iain Clarke, Warrior Programmer13-Aug-07 22:36

Iain Clarke, Warrior Programmer

13-Aug-07 22:36

First thing I would do is handle (at least as a test) WM_NCLBUTTONDOWN. Its quite possible that something is grabbing the down button, and then capturing the mouse until an UP comes along, bypassing you.

If you can't see the DOWN message, then you've probably not added the handler properly.

Another possibility...

The view itself doesn't actually *have* a caption bar - its provided by the CChildFrame in a non-maximised MDI frame, or the CMainFrame in a SDI app, or a maximised view. So you may be subclassing the wrong window!

Iain.

shutdown system on a particular time using vc++

p_13-Aug-07 19:06

13-Aug-07 19:06

hi all masters of vc
i want to know that how can i automaticlly
shutdown and logon system on a particular time in vc++
please help me
thanks Rose | [Rose]

Re: shutdown system on a particular time using vc++

Hamid_RT13-Aug-07 19:58

Hamid_RT

13-Aug-07 19:58

You can use of WM_TIMER and after a time use of ExitWindowsEx.

WhiteSky

array -- foo, &foo and &foo[0]

George_George13-Aug-07 18:36

George_George

13-Aug-07 18:36

Hello everyone,

I think if we define foo as char array, for example,

char foo [32];

then foo, &foo and &foo[0] should be the same, right?

For example, the following 3 statements are the same,

strcpy (foo, goo);
strcpy (&foo, goo);
strcpy (&foo[0], goo);

Any comments?

I am very interested in how C treats foo and &foo and make them the same?

thanks in advance,
George

Re: array -- foo, &foo and &foo[0]

jimfisher13-Aug-07 18:55

jimfisher

13-Aug-07 18:55

I think that you will find this to be compiler dependent.

foo is the array, so C/C++ treats the array name as a pointer to the array and thus it is a pointer of the same value as &foo[0].

With some compilers however, I have seen where the compiler stores a pointer to the array (like &foo[0] and then &foo is a pointer to that pointer... so I would stay away from this syntax.

Jim

Re: array -- foo, &foo and &foo[0]

George_George13-Aug-07 20:04

George_George

13-Aug-07 20:04

Thanks Jim,

I have tested that on Visual Studio, foo and &foo are the same. I think you mean on some other compiler, they may be different.

Here is my test program in Visual Studio.

<br />
int main (int argc, char** argv)<br />
{<br />
        char foo [1024];<br />
        unsigned int p;<br />
        unsigned int q;<br />
        p = foo;<br />
        q = &foo;<br />
<br />
        return 0;<br />
}<br />

I am interested in the cases when "&foo is a pointer to that pointer". I am wondering what is wrong if I still treat foo and &foo the same in this situation? Could you provide more information and analysis please?

regards,
George

Re: array -- foo, &foo and &foo[0]

jimfisher14-Aug-07 5:45

jimfisher

14-Aug-07 5:45

I do not recall where I have seen it. It was several years ago on an embedded compiler... seems like green hills or perhaps wind river. If you are using microsoft, I don't think you will have a problem treating foo and &foo as equals.

Jim Fisher

Re: array -- foo, &foo and &foo[0]

George_George14-Aug-07 16:11

George_George

14-Aug-07 16:11

Thanks all the same, Jim.

regards,
George

Re: array -- foo, &foo and &foo[0]

Iain Clarke, Warrior Programmer13-Aug-07 22:46

Iain Clarke, Warrior Programmer

13-Aug-07 22:46

I was a little intrigued by your question, and made up a little test...

UINT p, q;

char foo [100];

p = (UINT)foo;
q = (UINT) (&foo);

ASSERT(p == q);

char *bar = foo;

p = (UINT) bar;
q = (UINT) (&bar);

ASSERT(p == q);

And you were indeed right. foo and &foo were the same value, but bar and &bar were not. Part of the problem is that we're both cheating and looking at the variables as raw numbers (which I find useful to do conceptually), but the compiler has the advantage of looking at them knowing there type.

So foo is a number, but is known to be an array, while &foo happens through an implementation detail you can't rely on to be true on another day of the week to be the same number, but is treated differently as it has a different type (pointer to an array).

Hard casting like you did can be useful, but it can also be dangerous.

Short answer: compiler dependent. If you rely on it, prepare to be shot in the foot.

Iain.

Re: array -- foo, &foo and &foo[0]

George_George13-Aug-07 23:23

George_George

13-Aug-07 23:23

Thanks Iain,

So, the best practice is not to use &foo? Smile | :)

regards,
George

Re: array -- foo, &foo and &foo[0]

Iain Clarke, Warrior Programmer13-Aug-07 23:36

Iain Clarke, Warrior Programmer

13-Aug-07 23:36

There's nothing wrong with using &foo - but not as a number. Use it as a "pointer to an array" and let the compiler worry about location details.

"Is it wrong to do..." is not something I can possibly answer in the general case.

But taking your strcpy example...

char foo [100];

strcpy (foo, "iain");   is fine
strcpy (&(foo[0]), "iain"); is fine, but ugly
strcpy (&foo, "iain"); is syntactically wrong, and I'm surprised you don't get a warning at least. It just happens to work on this compiler.


char *bar = new char [100];

strcpy (bar, "iain");   is fine
strcpy (&(bar[0]), "iain"); is fine, but ugly
strcpy (&bar, "iain"); will fail - and mostlikely crash stuff.

As you see, the only difference between "getting away with it", and "failing" is what's written a few lines up, relying on &array == array is a really bad idea, even if you will always get away with it. Imagine you come back in 3 years, your boss says "this needs to be longer - make it dynamically sized", and your code will crash with you being puzzled.

Iain.

Re: array -- foo, &foo and &foo[0]

George_George13-Aug-07 23:50

George_George

13-Aug-07 23:50

Great comments, thanks Iain!

regards,
George

Disabling shortcut in Visual C++ [modified]

jimfisher13-Aug-07 18:15

jimfisher

13-Aug-07 18:15

In C code an if statement such as:
if(A || B)
will shortcut, i.e. if A is true, it will branch and not even check B.

On the other hand in the case of:
if(A && B)
a shortcut branch is taken if A is false and B is not even checked.

While this is often useful, I have a situation where I would like to disable shortcuts. Is this possible in VC++?

Jim Fisher

-- modified at 0:35 Tuesday 14th August, 2007

Re: Disabling shortcut in Visual C++

Iain Clarke, Warrior Programmer13-Aug-07 22:56

Iain Clarke, Warrior Programmer

13-Aug-07 22:56

Its pretty deep in the assumptions of C that you will have this shortcutting behaviour, and as you mention, is very useful.

ie.

if (pointer && pointer->otherpointer)
{
   ...
}

would crash if pointer was null, and there wasn't this shortcutting behaviour.

I'm assuming that A and B are complex expressions, or function calls.

In which case you can do...

BOOL A = Something_I_Insist_On_Being_Done ();
BOOL B = Other_Thing ();

if (A || B)
{
   ...
}

If a compiler flag did exist then you'd have terrible trouble understanding why you used it when you look back in two years time. To avoid that, you'd end up writing so many comments you may as well have done the preconditions early as I did in my example.

Iain.

ps. Never forget the impact on your successor - especially as that may be you on a monday morning with a hangover...

Re: Disabling shortcut in Visual C++

David Crow14-Aug-07 3:12

David Crow

14-Aug-07 3:12

It's called short-circuit evaluation, and has been part of C for decades. Why would you want to "disable" it?

"A good athlete is the result of a good and worthy opponent." - David Crow

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

Re: Disabling shortcut in Visual C++

jimfisher14-Aug-07 5:20

jimfisher

14-Aug-07 5:20

when building software for avionics (DO-178B) Level A (critical to safety) one must test every path in the code.

The difficult paths to prove they have been taken are generally the "shortcut" paths. Thus it is often easier to test the crash cases yourself as:

if(pointer != NULL)
{
if(pointer->object)
{
do whatever

One can still do this even with short cutting, it is just expressions such as:

if((A || B) && (C || D))

These have several shortcut paths.

To defeat this, one could convert the bools to unsigned int and

// no shortcutting on bit ops as the compiler thinks I need all 16 bits
X = (A | B) & (C | D);
if(X != 0)
{
do this or that

But this seems more awkward and harder to manage (code reviews etc) than just defeating the shortcut code generation...

Make sense or no?

Jim Fisher

fatal error C1001: INTERNAL COMPILER ERROR

itkid13-Aug-07 18:11

itkid

13-Aug-07 18:11

Hi,
I am using Visual Studio 6 for compilation of source code however i am getting "fatal error C1001: INTERNAL COMPILER ERROR". Can you pls help me to remove this compilation problem.

Thanks
Pankaj Smile | :)

Re: fatal error C1001: INTERNAL COMPILER ERROR

jimfisher13-Aug-07 18:20

jimfisher

13-Aug-07 18:20

MSDN Library says:
Fatal Error C1001
INTERNAL COMPILER ERROR
(compiler file 'file', line number)

This error is most often generated in one of two cases:

Failure to recover the compiler's internal state following detection of a syntax error in the program. The first pass of the compiler will occasionally fail when attempting to recover its state following the detection of a malformed program. Typically, the compiler will have printed an error message (or messages) and will later produce an internal compiler error. In most cases, fixing the errors reported in your code and recompiling will solve the problem.

Failure of the code generator to find a way to generate correct code for a construct. This is most often caused by the interaction of an expression and an optimization option. The optimization has generated a tree which the compiler does not know how to handle. Such a problem can often be fixed by removing one or more optimization options when compiling the particular function containing the line indicated in the error message.
If no error messages have been emitted prior to the internal compiler error, then the next step is to determine which pass of the compiler is emitting the internal compiler error. This can be determined by recompiling the application with the /Bd option included. The /Bd option will cause each pass to print its name and arguments when it is invoked. The last pass invoked before the error is emitted is the one responsible.

If the pass indicated is P1, then the likely problem is still error recovery, as in number one above, but it is happening before the compiler has had a chance to emit the error message for the error it has just discovered. In such a case, examine the line on which the internal compiler error is reported. This line may also contain an unreported syntax error. Fixing any errors you find on that line will solve the internal compiler error in most cases. If you cannot find any error on that line or on the line previous to the one reported, contact Microsoft Product Support Services for help.

If the pass indicated is P2, then the problem can usually be fixed by removing one or more optimization options (or using a different code generator). You can determine which option is at fault by removing them one at a time and recompiling until the message goes away. Generally the last one removed is the problem and all other optimizations can be used safely. The most common culprits are /Og, /Oi, and /Oa. Once the offending optimization is discovered, it need not be turned off for the entire compilation. The offending optimization can be disabled with the optimize pragma while compiling the function where the error occurred, but enabled for the rest of the module.

More rarely, such errors occur at very low optimization levels or even when optimization is disabled. In such cases, rewriting the line where the error is reported (or possibly several lines including the one causing the error) may be a solution. If none of these options works, consult the technical support help file or the technical support section in one of your manuals.

Jim

Re: fatal error C1001: INTERNAL COMPILER ERROR

itkid15-Aug-07 20:35

itkid

15-Aug-07 20:35

Thanks Jim for your reply however I am still facing same compilation problem after removing all /Og, /Oi, and /Oa option. In fact I am using the default VS 6.0 optimization option.

how to know a double is infinite directly?

includeh1013-Aug-07 18:00

includeh10

13-Aug-07 18:00

E.g.
double dbInf=1/sin(0);

currently I check it as:
//=====================
char sz[4096];
sprintf(sz,"%f",dbInf);
if(strchr(sz,'#')) //true means the double is infinite number.
//========================

in my program, I have million of doubles needed to be checked, above checking code is very slow.

my Q is:
how to check it directly without using sprintf() and strchr()?
or how to check it faster?

thx.

Re: how to know a double is infinite directly?

Maxwell Chen13-Aug-07 19:04

Maxwell Chen

13-Aug-07 19:04

There is the CRT function _finite(double)[^], but it is not working. Dead | X|

Maxwell Chen

Re: how to know a double is infinite directly?

Mark Salsbery14-Aug-07 6:05

Mark Salsbery

14-Aug-07 6:05

   #include <math.h>
   #include <float.h>

   ...

   double dbInf = 1.0 / sin((double)0);

   if (0 == _finite(dbInf))
   {
      // infinite
   }

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Application that use DataGrid ActiveX Control dont work without VC++ installed

xanagan13-Aug-07 17:13

xanagan

13-Aug-07 17:13

I tried to run my ActiveX-embled MFC Application on Computer with out VC++ install and It doesn't work

But It work on another computer with vc++ 6.0 installed

Can someone suggest the solution?

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.