Cleaning up strings

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!

Quote:

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Originally Posted by LeanA

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

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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.

Quote:

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

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

Quote:

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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.

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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

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

Hi Paul, and Victor, thanks for replying.

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

Thank you very much!

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 ?