Pointer to array of structs pointers - c++

Question

I need create one pointer to a null-terminated array of pointers to key detail structures..
Struct: WFS_RESULT
typedef struct _wfs_result
{
REQUESTID RequestID;
HSERVICE hService;
SYSTEMTIME tsTimestamp;
HRESULT hResult;
union {
DWORD dwCommandCode;
DWORD dwEventID;
} u;
LPVOID lpBuffer;
} WFSRESULT, *LPWFSRESULT;
Struct: PINKEY
typedef struct _wfs_pin_key_detail_ex
{
LPSTR lpsKeyName;
DWORD dwUse;
BYTE bGeneration;
BYTE bVersion;
BYTE bActivatingDate[4];
BYTE bExpiryDate[4];
BOOL bLoaded;
} WFSPINKEYDETAILEX, * LPWFSPINKEYDETAILEX;
Program: How am i trying to do
LPWFSPINKEYDETAILEX* array[7];
LPWFSPINKEYDETAILEX Test;
WFSPINKEYDETAILEX Obj;
Test = &Obj;
Test->lpsKeyName = NULL;
array[0] = &Test;
array[1] = &Test;
array[2] = &Test;
array[3] = &Test;
array[4] = &Test;
array[5] = &Test;
array[6] = NULL;
LPWFSPINKEYDETAILEX** val = array;
lpWFSResult->lpBuffer = val;
The question is, is what I did above a pointer to an array of pointers? Because, I need to pass this Pointer Array Pointer to this parameter lpWFSResult-> lpBuffer = val; and in the final program (Bank Application) it gives error -15 (WFS_ERR_INTERNAL_ERROR).

Answer 1

Just as idea. Maybe they check if to be different objects. Maybe they are using the previous pointers and do not expect that value of val[0] will be changed after changing val[1].
Also check the API maybe they expects the rest of the fields filled up
lpsKeyName
bGeneration
bActivatingDate
bExpiryDate

Answer 2

This depends on how the array is created and where it is stored/used. based on the code provided, I assume the array has been generated on the memory stack but then used after that stack level has been popped (ie. function returns). The array memory will have been deallocated and the array pointer will be invalid (will cause unexpected behaviour). If you need to preserve the array outside of the stack, you will need to generate it on the heap using new. This way the memory will persist after the function exits and the memory stack level is popped.
LPWFSPINKEYDETAILEX** array = new LPWFSPINKEYDETAILEX*[7];
LPWFSPINKEYDETAILEX Test;
WFSPINKEYDETAILEX Obj;
Test = &Obj;
Test->lpsKeyName = NULL;
array[0] = &Test;
array[1] = &Test;
array[2] = &Test;
array[3] = &Test;
array[4] = &Test;
array[5] = &Test;
array[6] = NULL;
lpWFSResult->lpBuffer = array;
Don't forget to delete it later when you're done with the memory so you don't get a memory leak.

Answer 3

You need to read the API spec where it tells you how to allocate memory. I presume you are writing an SP, have six keys and the key names are in the array keyNames.
int numKeys=6;
LPSTR keyNames[6]={"key1","key2","key3","key4","key5","key6"};
LPWFSRESULT pResult;
LPWFSPINKEYDETAILEX* ppDetails;
WFMAllocateBuffer(sizeof(WFSRESULT), WFS_MEM_ZEROINIT, (LPVOID*)&pResult);
WFMAllocateMore(sizeof(LPWFSPINKEYDETAILEX)*(numKeys+1),pResult, (LPVOID*)&ppDetails);
for (int i=0;i<numKeys;i++)
{
WFMAllocateMore(sizeof(WFSPINKEYDETAILEX),pResult,(LPVOID*)&ppDetails[i]);
WFMAllocateMore(strlen(keyNames[i])+1,pResult,(LPVOID*)&ppDetail[i].lpsKeyName);
strcpy(ppDetails[i].lpsKeyName,keyNames[i]);
//TODO fill in other details
}
ppDetails[numKeys]=NULL;
pResult->lpBuffer=ppDetails;