Cleaning up strings

[LeanA]

Hi all,

Given this code, I want to make sure that there are no leaks from the strings that I have used:

#include <atlstr.h>

...

string varVarName = GetAttribute("VarIn", pNodeMap);
string stringIn = getDictionary(varVarName);
CString cstrIn = CString(stringIn.c_str());
cstrIn.Trim();
CT2CA pszConvertedAnsiString(cstrIn);
std::string strOut(pszConvertedAnsiString);


From what I understand, I think that I do not need to free std::strings as the program automatically frees those. I am not sure regarding CStrings, although I also believe that the program handles those.

What I know is that from the many string types in C++, only BSTR require freeing if you have called AllocSysString on it or equate it to NULL.

Can you help me understand why you need to free BSTR and not std::string, CString, etc.?

Thank you!

[Paul McKenzie]

From what I understand, I think that I do not need to free std::strings as the program automatically frees those

Not quite. It isn't the program that frees the std::string, it's the std::string class itself that does the "freeing" when the variable goes out of scope. When the destructor of std::string is invoked, the memory that the std::string allocated is deallocated automatically.

I am not sure regarding CStrings, although I also believe that the program handles those.

Again, it isn't the "program" doing this -- it's CString's desctructor that does this.

What I know is that from the many string types in C++, only BSTR require freeing if you have called AllocSysString on it or equate it to NULL.

Well, this goes back to my earlier statements.

BSTR is not a C++ class, therefore it knows nothing by itself of when it goes out of scope or will not be used anymore.

Regards,

Paul McKenzie

[VictorN]

Well, BSTR is not convenient enough to work with.
_bstr_t class (a wrapper of BSTR) is much better in use.

[LeanA]

Hi Paul, and Victor, thanks for replying.

Thankyou for those inputs! I'll keep them in mind.

Thank you very much!

[Philip Nicoletti]

Off topic to the question that you posed:

It looks like you are:

1) taking a std::string and converting it to a CString
2) trimming the CString
3) converting back to a std::string

Why not just trim the std::string directly ?