Need urgent help.

[drazbliz]

Hello,

I am running the following code segment in visual studio 2005.

size_t cchSize = 10*sizeof(TCHAR);
LPTSTR temp = (LPTSTR)malloc(cchSize);
temp[0] = '\0';
_tcscat_s(temp, cchSize, _T("hello"));
free(temp);

It fails at the statement -

free(temp)

with the error:

Heap block at 00A57F80 modified at 00A57FC0 past requested size of 38.

If i change _tcscat_s to deprecated _tcscat there is no error. Can
anyone throw some light on this?


Thanks,
C++Programmer.

 

[Ben Pope]

Hello,

I am running the following code segment in visual studio 2005.

size_t cchSize = 10*sizeof(TCHAR);
LPTSTR temp = (LPTSTR)malloc(cchSize);
temp[0] = '\0';
_tcscat_s(temp, cchSize, _T("hello"));
free(temp);

It fails at the statement -

free(temp)

with the error:

Heap block at 00A57F80 modified at 00A57FC0 past requested size of 38.

If i change _tcscat_s to deprecated _tcscat there is no error. Can
anyone throw some light on this?

Not really, those functions starting with an underscore do not exist in
C++ and I have no idea what they do. Perhaps you should ask in a
newsgroup where those functions are topical, perhaps one with microsoft
and windows in the name.

Ben Pope

 

[Daniel T.]

Hello,

I am running the following code segment in visual studio 2005.

size_t cchSize = 10*sizeof(TCHAR);
LPTSTR temp = (LPTSTR)malloc(cchSize);
temp[0] = '\0';
_tcscat_s(temp, cchSize, _T("hello"));
free(temp);

It fails at the statement -

free(temp)

with the error:

Heap block at 00A57F80 modified at 00A57FC0 past requested size of 38.

If i change _tcscat_s to deprecated _tcscat there is no error. Can
anyone throw some light on this?

I believe that if you put the above code in a main all by itself, the
error will go away as well. If not, then probably _tcscat_s doesn't do
what you think it does and is writing past the requested size.

I can't help but wonder how big a TCHAR is if 10 * sizeof(TCHAR) ends up
equaling 38...

 

[Phlip]

I am running the following code segment in visual studio 2005.

size_t cchSize = 10*sizeof(TCHAR);
LPTSTR temp = (LPTSTR)malloc(cchSize);
temp[0] = '\0';
_tcscat_s(temp, cchSize, _T("hello"));
free(temp);

Why on Earth are you not using a CString, a CStringW, or a _bstr_t?

And why are you using a strcat() derived method when you could use a
strcpy() derived method, or even a _tcsdup()?

And why malloc() in a C++ program?