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I declare a class CChildView2 derived from CView, and change the constructorr's and destructor's attribute from protect to public,
and declare a member variable in CMainFrame as m_wndView2, then replace the original m_wndView with m_wndView2, every thing is well except that when I close the application, there is an exception. What's the problem?
I tracked it, but found nothing.
the problem ocuurs here:
void CView::PostNcDestroy()
{
// default for views is to allocate them on the heap
// the default post-cleanup is to 'delete this'.
// never explicitly call 'delete' on a view
delete this;
}
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CChildWnd is derived from CWnd not CView,
CView will delete itself after the view is destroyed, in PostNcDestroy.
It can't be delete twice.
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Hi,
Currently I am implementing a dll that will be used in the VB application for identifying the multiple mice.
In the C++ dll I have to write the code to receive the RawInputData that will contain the HID, and based on the HDI I can identify the different mouse.
But as I searched in the MSDN I can collect the raw input information HID only inside the WndProc function with the WM_INPUT message.
Please let me know, Is there any way to receive the HID for mouse without WndProc function.
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hello every one,
I am using RegEnumValue function to enumerate the registry values of a open key. I want to know how does it enumerate the values i mean in sorted manner or in different manner. pls help me.
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yudhisthira wrote: I want to know how does it enumerate the values i mean in sorted manner
From the docs:
"Because values are not ordered, any new value will have an arbitrary index.
This means that the function may return values in any order."
I take that to mean any order 
Mark
Mark Salsbery
Microsoft MVP - Visual C++
![Java | [Coffee]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/coffee.gif)
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As Mark said, the order is not defined. If you want them in a particular order you'll have to enumerate the lot then sort them yourself.
Steve
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as it displayed in registry !
"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow
Never mind - my own stupidity is the source of every "problem" - Mixture
cheers,
Alok Gupta
VC Forum Q&A :- I/ IV
Support CRY- Child Relief and You
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Hello everyone,
The compile error of the following code is,
foo.cpp(7) : error C2146: syntax error : missing ';' before identifier '_'
foo.cpp(7) : error C2065: '_' : undeclared identifier
foo.cpp(7) : error C2143: syntax error : missing ';' before 'string'
I do not know why there is errors. I think in MERGE macro, the value of parameter a is hello and the value of parameter b is world in my case, and I defined hello_world to "H E L L O", it should be fine...
Any ideas?
<br />
#define MERGE(a,b) a ## _ ## b<br />
#define hello_world "H E L L O"<br />
<br />
int foo()<br />
{<br />
char* p0;<br />
p0 = MERGE("hello", "world");<br />
<br />
return 0;<br />
}<br />
thanks in advance,
George
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This macro invocation expands to the following:
"hello"_"world"
This is not a legal C++ statement.
Steve
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Thanks Steve,
I am a little confused. When I input MERGE ("hello", "world"), since the definition of MREGE (a, b) is a##_##b, and the value of parameter a is hello and the value of parameter b is world, the result should be hello_world, what is wrong with my above analysis? Why it will result in "hello"_"world"?
regards,
George
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Firstly this page on Token-Pasting[^] may be of interest; a Google[^] search on the topic may also be of interest. If you wanted a macro to do what you're after this would do the trick (I'm not sure why you'd want one however):
#include <iostream>
using namespace std;
#define MERGE(f, s) f s
void main()
{
cout << MERGE("Hello ", "world!") << endl;
}
Steve
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Thanks Steve,
It is my pure technical interest.
Your code works, cool!
regards,
George
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If my guess is correct, you're trying to do something like the following:
#define MERGE(a,b) a##_##b
#define hello_world "H E L L O"
int main()
{
char* p0;
p0 = MERGE(hello, world);
printf("%s\n", p0);
return 0;
}
the above code compiles and sets p0 = " H E L L O"
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
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Thanks CPallini,
Your code works. But why my code is not working? I just changed MERGE (hello, world) to MERGE ("hello", "world").
I think if I input MREGE ("hello", "world"), then the result will be hello_world by the definition of MERGE macro, then by the hello_world macro, the result should be "H E L L O".
What is wrong with my code?
regards,
George
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George_George wrote: What is wrong with my code?
The double quotes ".
If you need to build the hello_world macro then you have to merge hello with world.
As it stands, your code produces "hello"_"world" that is just a sintax error.
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
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Thanks CPallini,
Cool!
regards,
George
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The best way to solve such problems is to see the code as the compiler is seeing it. Compile with the /P or /E switch and look at the preprocessor output.
"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
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Thanks DavidCrow,
It works! Cool!
regards,
George
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I have the following code to read data from a list of files. The code read the first file and read the data correctly. I used break point debug and found at "fclose(f_ptr2)" giving error: "Access Violation"
//
FILE *f_ptr2;
//
//
for (int ii=0;ii
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Review and correct your post: the for loop can't be properly seen and some indentation wouldn't hurt either.
Steve
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Also, do you check the return value from fopen()?
Mark
Mark Salsbery
Microsoft MVP - Visual C++
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Hi,
I am using SetupDiGetClassDevs() API to retrieve some information related to Battery, but while using "GUID_DEVICE_BATTERY" macro, Visual Studio 8 gives linker error that "unresolved external symbol _GUID_DEVICE_BATTERY".
What could be reason for this?
I have verified for appropriate libraries.
Whenever I build this project in VC++ 6.0, it gets build successfully.
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I have looked for the symbol myself in the LIBs that come with Visual Studio 2005 and, sure enough, it wasn't there.
So I guess you'd have to define it yourself:
const GUID GUID_DEVICE_BATTERY = {0x72631e54L, 0x78A4, 0x11d0, {0xbc, 0xf7, 0x00, 0xaa, 0x00, 0xb7, 0xb3, 0x2a }};
Florin Crişan
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GUID_DEVICE_BATTERY is defined in the BatClass.h file and internally uses the DEFINE_GUID macro. You must include <initguid.h> in one of your source files before you include BatClass.h.
Judy
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I am working on hashing homework code and i have hit a wall.
The first time through a while loop, it works fine, but every time after that, it is not working correctly.
The output currently looks like:
ending address: Cluster size:
4 5 <- this is correct
97 0 <- this should be 1
116 0 <- this should be 1
241 5 <- this should be 6
Here is the code i wrote:
void HashTable::clusterCount(void)
{
unsigned long numClusters=0;
unsigned long clusterLength=0;
unsigned long i=0;
unsigned long totalLength = 0;
while(i<tableSize)
{
//startCluster=clusterLength;
clusterLength = 0;
while((i<tableSize)&&(hashTableArray[i]!=0)){
clusterLength++;
i++;
}
totalLength += clusterLength;
cout<< (i-1) <<" "<< clusterLength <<endl;
while((i<tableSize)&&(hashTableArray[i]==0))
{
i++; // increments i when the array address is empty
}
numClusters++;
i++;
}
cout<<"average cluster Length "<<totalLength/numClusters<<endl;
cout<<"numClusters "<<numClusters<<endl;
}
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