CODEWITHSUNDEEP
c++mallocmemcpy
Shahriyar
Shahriyar

Reputation: 1583

C++ memcpy to a malloc'ed memory


I have the following code and it works well :

int Size ;
CString Message ;
BYTE Buffer[256] ;
Message = _T("Some Text") ;
Size = Message.GetLength() * sizeof(WCHAR) ;
memcpy(Buffer,&Message,Size) ;

But when i change it to this :

int Size ;
CString Message ;
BYTE* Buffer ;
Buffer = (BYTE*) malloc(256) ;
Message = _T("Some Text") ;
Size = Message.GetLength() * sizeof(WCHAR) ;
memcpy(Buffer,&Message,Size) ;

And then check the Buffer data, it populated with some random trash bytes

What's wrong ?

Upvotes: 1

Views: 1458

Answers (2)

BartoszKP
BartoszKP

Reputation: 35891

BYTE Buffer[256] creates an array of 256 BYTE-sized elements, regardless of BYTE's size. malloc(256) on the other hand allocates 256 bytes of memory. Try malloc(256 * sizeof(BYTE)).

Upvotes: 3

sehe
sehe

Reputation: 393134

CString is not a POD type and cannot be bitwise copied.

It seems you have to switch paradigms from C to C++

From the docs it seems like http://msdn.microsoft.com/en-us/library/aa300569(v=vs.60).aspx supports a conversion:

LPCTSTR raw = (LPCTSTR) Message;
// now memcpy from `raw`

Upvotes: 4

Related Questions