Calloc Problem

Good Evening Everyone,

Before I get started I think I should tell you all that I am a VB programmer, trying to learn C++. To make it worse, my C++ project, is on Intel Dialogic products. And that means most of the examples, are written in standard C. Anyways, I got this code script down from 137 errors down to one error. The error is:

error C2440: '=' : cannot convert from 'void *' to 'BOARD_INFO *' Conversion from 'void*' to pointer to non-'void' requires an explicit cast

The definition of BOARD_INFO is:

Code:

typedef struct  {
	char		name[BUFF_LEN];
	int*		pChDev;
	FEATURE_TABLE*			pFT;
	ct_devinfo*			pDevInfo;
	char		nameB[BUFF_LEN];
	char		nameC[BUFF_LEN];
	char		buff[BUFF_LEN];
	int			dev;
	int			nr;
	int			err;
	int			line;
	DX_IOTT*	plott;
	char		nmC[1024];
	int			bd, ch;
	int			bdV, chV;
	char*		pChannel[BUFF_LEN];
	long		devBRD;
	LINEDEV*	pLineDev;
	int			nrChannels;

} BOARD_INFO;

I have the following line declaring a global array of BOARD_INFO:

Code:

BOARD_INFO*		gBoardInfo;

The line I am getting the error on is:

Code:

gBoardInfo = calloc (gBoardCount,sizeof(BOARD_INFO));

gBoardCount is an integer.

I do not understand the error. I mean I do, but I don't know how it is becoming an error. Let me say what I think the error is saying, and maybe someone can correct my problem, and maybe even explain the error so that it makes sense to me if I should encounter it again.

error C2440: '=' : cannot convert from 'void *' to 'BOARD_INFO *' Conversion from 'void*' to pointer to non-'void' requires an explicit cast

I know that gBoardInfo is an array that hasn't been defined in size. The function will allocate X arrays of BOARD_INFO. But I just don't understand how it see's a "Void" being returned. I dunno, maybe none of what I said makes sense. . . Just wish it.

You need to corece the type of the calloc:
(gBoardInfo *)(calloc ........)
Alternatively and more C++ would be to use new and delete.
IF you are new to C++ you might want to consider maing it a class, rather than a struct too. Depends on what you are doing.
I recommend a good C++ book before you go too far wrong. C++ really does require the right mindset from the start or you can end up in an awful mess.

Good luck!

the void* pointer was intoduced to C as a pointer type that can
be set to other pointer types - i think it predates casts (making
one data type look like another). the line of code is legal in
C since that's what the void pointer was designed for (calloc
returns void*), but C++ introduced stronger type checks to
prevent potential programming errors. To get around it, just use
a simple C style cast - you're line of code becomes the folllowing:

Code:

gBoardInfo = (BOARD_INFO*) calloc (gBoardCount,sizeof(BOARD_INFO));

Here's a more detailed explanation of the issue

[correction]
>>(gBoardInfo *)(calloc ........)

gBoardInfo is a variable name - a cast involves a data type -
so michaels-r's method is wrong
[/correction]

Thanks for the correction - teach me to answer questiosn late at night when my wife is telling me to leave the **** computer alone! :-)