Re: Structure Value is not getting updated - C / C++ / MFC Discussion Boards

sakthii10-Jun-09 4:59

10-Jun-09 4:59

I created a form application
File->New->Project->VC++->Windows Form Application.

I created couple of .Cpp files and .h files.

I have structure defined in .h file

typedef struct _PHB_ENTRY
{
unsigned char name[30];
unsigned char add[50];
int checksum;
int lenght;
int reserverd1;
int reserved2;
} PHB_ENTRY;

I have declared a variable in .cpp file, which is nothing but a 'C' code.

PHB_ENTRY myEntry[50];

First i have init function, thought to initialize the struc with null, so i used memset

memset(myEntry,NULL,50);

Problem no #1: I cant see index 0 is intialized to NULL !

then i started initializing the struct

strcpy((char*)myEntry[1].name,"STEFY");
Probmelem no #2: I can see STEFY being copied from myEntry[1].name[4], first for bytes are empty , that is myEntry[1].name[0]...myEntry[1].name[3] are empty!!

i assigned other values.

myEntry[1].checksum = 13;
myEntry[2].length = 4;
Problem no: #3: I see 13 is getting updated in myEntry[1].resevered1 variable and i cant see myEntry[2].length getting updated!

can some one help me out on this strange problem?!
Just a simple C code though!!!

Re: Structure Value is not getting updated

«_Superman_»10-Jun-09 5:18

«_Superman_»

10-Jun-09 5:18

The memset is has to be done as memset(myEntry, 0, sizeof(PHB_ENTRY) * 50);
Rest of your code looks ok.
Probably something wrong in how you are validating it.

«_Superman_»
I love work. It gives me something to do between weekends.

Re: Structure Value is not getting updated

Stephen Hewitt10-Jun-09 5:25

Stephen Hewitt

10-Jun-09 5:25

sakthii wrote:
Problem no #1: I cant see index 0 is intialized to NULL !

memset's third parameter is a byte count. Your array is 50 elements long, not 50 bytes. Try something like this:

memset(myEntry, 0, sizeof(myEntry));

Steve

Re: Structure Value is not getting updated

Roger Stoltz10-Jun-09 5:42

Roger Stoltz

10-Jun-09 5:42

There seems to be two issues here:

The initialization of the myEntry array.
Assigning values to the members end up at erroneous locations.

#1 has already been addressed by others and should be

memset( myEntry, 0, sizeof( PHB_ENTRY ) * 50 );
// or
memset( myEntry, 0, sizeof( myEntry ) );

The second one seems a little trickier, but for some reason the compiler seems to think that the members of the structure starts four bytes later. Have you possibly removed a four-byte member from the beginning of the structure?
Try and rebuild the complete application as there seems to be a modification done but the object file has not been rebuilt and rebuilding usually fixes these kind of problems.

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Re: Structure Value is not getting updated

Randor 10-Jun-09 6:05

Randor

10-Jun-09 6:05

Hi sakthii,

In addition to what the other members said you can remove the call to memset completely. You can do this to initialize your array to zero:

PHB_ENTRY myEntry[50] = {0};

Best Wishes,
-David Delaune

Re: Structure Value is not getting updated

David Crow10-Jun-09 7:47

David Crow

10-Jun-09 7:47

sakthii wrote:
Problem no: #3: I see 13 is getting updated in myEntry[1].resevered1 variable...

Even though you are not assigning anything to it?

sakthii wrote:
can some one help me out on this strange problem?!

How are you verifying the values?

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Re: Structure Value is not getting updated

sakthii10-Jun-09 20:14

sakthii

10-Jun-09 20:14

Thanks to all, memset problem is solved, i could see the structure is set with 0.

sakthii wrote:
Problem no: #3: I see 13 is getting updated in myEntry[1].resevered1 variable...

Even though you are not assigning anything to it?

No. it happens when I am assigning the value to other parameter like myEntry[1].length= 4

How are you verifying the values?

verifying using step by step debugging, I am using Visual Studio 8.

Re: Structure Value is not getting updated

Cedric Moonen10-Jun-09 20:24

Cedric Moonen

10-Jun-09 20:24

sakthii wrote:
verifying using step by step debugging, I am using Visual Studio 8.

And how do you verify the values ? Are you looking at the variables directly (within the watch window for instance) or are you looking up at the raw memory because you know where your member are located in memory ?

Cédric Moonen
Software developer

Charting control [v2.0]
OpenGL game tutorial in C++

Re: Structure Value is not getting updated

sakthii11-Jun-09 0:30

sakthii

11-Jun-09 0:30

I am using watch window.

I created new project (windows console application) and added the file to it and same code is working!!!

I think some problem with the Windows Forms Aplication. problem with IDE ?!

Re: Structure Value is not getting updated

chirag_chauhan10-Jun-09 20:46

chirag_chauhan

10-Jun-09 20:46

Problem#2 & 3 seems to be occur because of memory-overusage that leads memory corruption at some un-imagined places, I have observed this kind of behavior mostly with mobile technologies. I suggest you to use heap-allocation instead of stack-allocation or try to reduce the array size.

MCF question

Anderson Jogie10-Jun-09 4:38

Anderson Jogie

10-Jun-09 4:38

Do anyone know how to convert a vector to a list in Visual C++?
I tried casting, it does not work for me.

Re: MCF question

Maximilien10-Jun-09 4:42

Maximilien

10-Jun-09 4:42

Are you talking about a std::vector and a std::list ?

Don't think there is a direct conversion, you will need to copy from one to the other.

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Re: MCF question

Anderson Jogie10-Jun-09 4:55

Anderson Jogie

10-Jun-09 4:55

Yes : std::vector to std::list

What is the best method to copy the data? Can you give an example?

Thanks.

Re: MCF question

David Crow10-Jun-09 5:02

David Crow

10-Jun-09 5:02

It's not MFC, but something like:

vector<int> vec;
vector<int>::iterator it;
list<int> l;
 
for (it = vec.begin(); it != vec.end(); it++)
    l.push_back(*it);

Re: MCF question

Anderson Jogie10-Jun-09 7:22

Anderson Jogie

10-Jun-09 7:22

I forget to mention it's two different data types see code below:

std::list<rdlresource*> TempRes;
TempRes.clear;
std::vector<rdltemporaryresource*>::iterator it;

for (it = TempResList.begin(); it != TempResList.end(); it++)
TempRes.push_back(*it);

Thanks the help on this.

Re: MCF question

Anderson Jogie10-Jun-09 9:54

Anderson Jogie

10-Jun-09 9:54

Well I guess it did not compile fully earlier, I am still getting the compiler error message below when I tried to copied the data from a vector to a list.

ompiling...
FSSCHED.CPP
c:\program files\ilps\code\fstool\fssched.cpp(1165) : error C2664: 'push_back' : cannot convert parameter 1 from 'class RDLTemporaryResource *' to 'class RDLResource *const & '
Reason: cannot convert from 'class RDLTemporaryResource *' to 'class RDLResource *const '
Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
Error executing cl.exe.

fstool.dll - 1 error(s), 0 warning(s)

Re: MCF question

David Crow10-Jun-09 10:40

David Crow

10-Jun-09 10:40

That's because your list is for RDLResource* objects while your iterator for that list is for RDLTemporaryResource* objects.

Re: MCF question

Anderson Jogie10-Jun-09 11:49

Anderson Jogie

10-Jun-09 11:49

Right. So I am having problems transferring the data from the vector to the list.
How do I work around doing that in my case? I tied casting, it compiled but the application crashes at runtime.

Thanks.

Re: MCF question

David Crow10-Jun-09 11:58

David Crow

10-Jun-09 11:58

Anderson Jogie wrote:
How do I work around doing that in my case?

That's impossible to tell since I know nothing of either of those two classes. For example, how would you copy a vector of Automobile objects to a list of Animal objects?

Anderson Jogie wrote:
I tied casting, it compiled but the application crashes at runtime.

That would not work unless the two classes had a "is a" relationship.

Re: MCF question

Jim Crafton11-Jun-09 3:49

Jim Crafton

11-Jun-09 3:49

DavidCrow wrote:
That would not work unless the two classes had a "is a" relationship.

Reading that it occurred to me that a more casual (possibly less informed) reader might look at that, pause, and then have their head explode. Smile | :)

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Re: MCF question

David Crow12-Jun-09 2:36

David Crow

12-Jun-09 2:36

I agree.

Re: MCF question

Maximilien10-Jun-09 5:02

Maximilien

10-Jun-09 5:02

I'm not an STL expert, but after a quick google (bing did not give valid answers in the first few pages), here are a couple of solutions (adapt to your particular situation)

std::copy (v.begin (), v.end (), std::back_inserter (l))

std::list<int> l(v.begin(), v.end());

or ...

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Re: MCF question

Jim Crafton11-Jun-09 3:50

Jim Crafton

11-Jun-09 3:50

So you binged it, but it bonged out?

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SELECT * FROM User WHERE Clue > 0
0 rows returned
Save an Orange - Use the VCF!
Personal 3D projects
Just Say No to Web 2 Point Oh

Re: MCF question

Dustin Henry10-Jun-09 7:01

Dustin Henry

10-Jun-09 7:01

Just so you know, std::vector and std::list have nothing to do with MFC. They are part of STL or Standard Template Library and are cross platform.

How do I get the handle of a dialog in Visual C

jonsey2984710-Jun-09 4:15

jonsey29847

10-Jun-09 4:15

Hello,

I am porting a Dialog based application that I used Lcc-Win32 to develop over to Visual C++.

How to I get the handle of my Dialog box?

Thanks in advance for your help.

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