Access Violation when Initializing varia...

Access Violation when Initializing variables in a function

leeand00 (13)

Hi,

I'm rather new to Cpp and I can't understand why I keep getting an Access Violation, when I initialize something in another function (in Java we'd do this sort of thing all the time)

void somefunction(void * Data) { short DateStart, DateEnd; char * SalesRep, * Customer, * Master; int Detail; BOOL Group; OrdjourParamInit(Data, DateStart, DateEnd, SalesRep, Customer, Master, Detail, Group); // ... // And then SalesRep causes an Access Violation (wtf)? memcpy(Socket->sData+ip,SalesRep,strlen(SalesRep)+1); // ... }

void OrdjourParamInit(void * Data, short &DateStart, short &DateEnd, char * SalesRep, char * Customer, char * Master, int &Detail, BOOL &Group) { DateStart=*(short *)frmInterview->GetPrompt(ORDJOUR_FROM)->Data; DateEnd=*(short *)frmInterview->GetPrompt(ORDJOUR_TO)->Data; SalesRep=frmInterview->GetPrompt(ORDJOUR_REP_CODE)->Data; Customer=frmInterview->GetPrompt(ORDJOUR_CUSTOMER_CODE)->Data; Master=frmInterview->GetPrompt(ORDJOUR_MASTER_CUSTOMER_CODE)->Data; Detail=frmInterview->GetCombo(ORDJOUR_DETAIL)->GetSelection(); Group=frmInterview->GetCheckBox(ORDJOUR_GROUP_REP)->GetValue(); }

Is there any way to do this other than declaring everything as global variables?

Thanks you,
leeand00

Jeff HS (71)

The same way you do in java. Use classes.

guestgulkan (231)

or use pointers to pointers instead .

Zaita (1138)

What your doing looks fine to me.


SalesRep=frmInterview->GetPrompt(ORDJOUR_REP_CODE)->Data;

You have to make sure this is actually returning a pointer to data that isn't going to be cleared elsewhere.


memcpy(Socket->sData+ip,SalesRep,strlen(SalesRep)+1);

You shouldn't be using the +1, because there isn't a +1 character in SalesRep, not unless you put it there urself. Does sData+ip have the correct amount of memory allocated etc.

guestgulkan (231)

Sorry Zaita - I can't let this one go (at least until proven wrong). I think it should look like this (I'm only interested in the char* pointers):

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

void somefunction(void * Data)
{	
	short DateStart, DateEnd;	
	char * SalesRep, * Customer, * Master;	
	int Detail;	
	BOOL Group;	
	OrdjourParamInit(........, &SalesRep, &Customer, &Master,.....);

	memcpy(Socket->sData+ip,SalesRep,strlen(SalesRep)+1);         


void OrdjourParamInit(...... char **SalesRep, char **Customer, char **Master,.....)
{
	//.... other code 
	
	*SalesRep=frmInterview->GetPrompt(ORDJOUR_REP_CODE)->Data;
	*Customer=frmInterview->GetPrompt(ORDJOUR_CUSTOMER_CODE)->Data;
	*Master=frmInterview->GetPrompt(ORDJOUR_MASTER_CUSTOMER_CODE)->Data;

	//... other code
}

(This also assumes/hopes that the frmInterview is returning valid char pointers)

Zaita (1138)

You are indeed correct gulkan. I didn't think this one through properly :D

The pointer is passed by value, so a copy is made =\ Hence the pointer to pointer.

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