C++ nested structure with array

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i have pass a nested structure into a dll function,
it return "Access Violation from the dll function.

Is my code have any problem ?
Thank you so much

What I have tried:

#define CM24_NUMDEPCASSETTE			24

typedef struct SNOTETYPE
{
	char Notetype[6];
	int NumNote;
}SNOTE;

struct SWITH
{
	int OutNumber;
	SNOTE Types[CM24_NUMDEPCASSETTE * 4]; 
};

// Here is the function, i use LoadLibrary
typedef int (WINAPI*FNPTR) (SWITH RequestBankNot, SWITH WithdrawData);


FNPTR fnWithdraw = (FNPTR)GetProcAddress(Hinst, "InterDoWithdrawall");
if (fnWithdraw)
{
	SWITH vWithdrawall, vWithdrallData;
	vWithdrawall.OutNumber = 0;
	vWithdrawall.Types.NumNote = 1;
	strncpy_s(vWithdrawall.Types.Notetype, sizeof(vWithdrawall.Types.Notetype), "CPEA", sizeof(SNOTETYPE::Notetype));

	vWithdrallData.OutNumber = 0;
	vWithdrallData.Types.NumNote = 0;
	
       
	int Result = fnWithdraw(vWithdrawall, vWithdrallData); // here it prompt me error message
	std::cout << "\nResult:\n", Result;
}

Posted 9-Oct-19 23:04pm

chillichong

Updated 13-Oct-19 22:42pm

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CPallini 10-Oct-19 5:22am

You didn't post the InterDoWithdrawall function code.

2 solutions

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Richard MacCutchan · Answer 1 · 2019-10-09T23:46:00

Solution 1

That code will not compile.

C++

vWithdrawall.Types.NumNote = 1;

// Types is an array so needs an array index to be addressed correctly
//

Posted 9-Oct-19 23:46pm

Richard MacCutchan

Comments

chillichong 10-Oct-19 21:23pm

the code will be something like "vWithdrawall.Types[0].NumNote = 1;"

Am i have to fill all array then send to the function or i just send 1 row of data to the function?

Thank you

Richard MacCutchan 11-Oct-19 3:49am

How can we know what you have to send? Look at the documentation for the DLL or ask the people who wrote it.

chillichong 14-Oct-19 3:56am

i have change something on my code, but it still give same error.
Please give me some advice, Thank you

#define CM24_NUMDEPCASSETTE 24

typedef struct SNOTETYPE
{
char Notetype[6];
int NumNote;
}SNOTE;

typedef struct SWITH
{
int OutNumber;
SNOTE Types[CM24_NUMDEPCASSETTE * 4]; //[CM24_NUMDEPCASSETTE * 4]
}SWITHDRAWALL;
typedef SWITHDRAWALL *PASWITHDRAWALLCASS;

typedef int (WINAPI*FNPTR) (SWITHDRAWALL RequestBankNot, SWITHDRAWALL WithdrawData);

FNPTR fnWithdraw = (FNPTR)GetProcAddress(Hinst, "InterDoWithdrawall");
if (fnWithdraw)
{
struct SWITH *ptrWithdrawall, stWithdrawall;
struct SWITH *ptrWithdrawdata, stWithdrawdata;

ptrWithdrawall = &stWithdrawall;
stWithdrawall.OutNumber = 0;
stWithdrawall.Types[0].NumNote = 1;
strncpy_s(stWithdrawall.Types[0].Notetype, sizeof(stWithdrawall.Types[0].Notetype), "CPEA", sizeof(SNOTETYPE::Notetype));

ptrWithdrawdata = &stWithdrawdata;
stWithdrawall.OutNumber = 0;
stWithdrawall.Types[0].NumNote = 0;
strncpy_s(stWithdrawall.Types[0].Notetype, sizeof(stWithdrawall.Types[0].Notetype), "", sizeof(SNOTETYPE::Notetype));

int Result = fnWithdraw(stWithdrawall, stWithdrawdata);
std::cout << "\nResult:\n", Result;

Richard MacCutchan 14-Oct-19 4:42am

See below.

Richard MacCutchan · Answer 2 · 2019-10-13T22:43:00

Solution 2

C++

int Result = fnWithdraw(stWithdrawall, stWithdrawdata);

You are passing the complete structures to your dll function instead of the pointers. This should have been shown up by the compiler.
The correct code (I assume) should be:

C++

int Result = fnWithdraw(ptrWithdrawall, ptrWithdrawdata);

Posted 13-Oct-19 22:43pm

Richard MacCutchan

Updated 13-Oct-19 22:44pm

v2