C/C++ Structure behavior

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Hello C/C++ Guru:

I have a small questions in the behavior of Structure, I have declare a structure with 10 components. Some of the components in the structure has already their value but when I use

the structure components in a function DLL function those value I set previously has been deleted or empty. I don't know what is the problem... can someone else out there help me

Regards,
Byze

Posted 30-Oct-13 21:41pm

kpax1684

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Mohibur Rashid 31-Oct-13 4:09am

let us see the code

Fredrik Bornander 31-Oct-13 4:10am

We need to see how your using or passing the initialized struct.

kpax1684 31-Oct-13 5:25am

Here is my code..,

<pre lang="cs">typedef struct s_StudentPro
{
char Prog1[15];
char Prog2[15];
char Student1[15];
char Student1[15];
} s_STUDENTPRO;</pre>

short __stdcall DLLEXPORT CheckStudP(char STD[50], void *Mom)
{

<pre lang="cs">s_STUDENTPRO*sTudent;
sTudent= mom;
sTudent= calloc(1,sizeof(struct sTudent));</pre>

sprintf(sTudent->Prog1,"SuperCompT");
sprintf(sTudent->Prog2,"SuperCompT");

std_GetInfo(sTudent->Prog1, sTudent->cbOrderVersion, sTudent->Student1, sTudent->Student1, &dllStp);

Richard MacCutchan 31-Oct-13 6:31am

You have two fields with the same name (Student1), and a field name that does not exist (sTudent->cbOrderVersion) so this will not even compile. Try using copy and paste to paste your exact code into your original question, using the Improve question link.

Aescleal 31-Oct-13 4:23am

What the previous commentators said plus are you using C or C++?

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KarstenK · Answer 1 · 2013-10-30T22:25:00

your structure has some memory which can have random values. (That behavior isnt defined in C!!!). So you better initialize all components with proper values of your struct.

Consider using a class with its components, so you can deploy a useful constructor, destructor and some functionality.

Aescleal · Answer 2 · 2013-10-31T00:34:00

Answer these questions then see what happens:

- Why are you assigning a void pointer to your local pointer then immediately writing over it?

- why have you two structure members with the same name?

- why are you accessing a member of the structure (cbOrderVersion) that doesn't exist in the structure definition?

I'm surprised that lot even compiles TBH.

C/C++ Structure behavior

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