Structure Value is not getting updated

sakthii

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!!!

_Superman_

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.

Stephen Hewitt

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

Roger Stoltz

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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Lost User

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

David Crow

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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sakthii

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.

Cedric Moonen

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++

chirag_chauhan

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.

sakthii

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 ?!