A question about declspec property

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I have a definition like this in my class

public:
__declspec(property(get = getName, put = putName)) wstring Name;
wstring getName()	        {return m_sName;}
void putName(wstring Value)	{m_sName = Value;}

private:
wstring	m_sName;

but when I do this, it would not get the correct pointer

TCHAR* tcharStr = const_cast<TCHAR*>(m_vecMFC[nMfcIndex]->Name.c_str());

Suppose these is a string like in the memory of m_sName:
41 00 72 00 32 00 20 00 32 00 32 00 00 00
but when I read memory of tcharStr, it becomes:
00 00 72 00 32 00 20 00 32 00 32 00 00 00

So, it becomes a NULL string.

But Why? Can anybody give me some idea??

Thanks!

Posted 28-Apr-11 17:45pm

xchftt

Updated 28-Apr-11 21:15pm

Hans Dietrich

v2

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tolw · Accepted Answer · 2011-04-28T19:36:00

It's not a good idea to store the pointers you get from c_str() calls. It is a much better idea to make a copy of the string using _tcscpy.

As to why it fails - because the method is declared like this:

wstring getName()

What you get when you call it is a copy of m_sName - which than disappears pretty quickly. And that's why the pointer you get from c_str() is no longer valid and strange things may happen (it may even work in release for a while and than fail out of the blue). If you want the actual m_sName you would need to define the function like this:

wstring& getName()

You can even have both functions in your code and than compare the pointers c_str() returns - see the difference?

But as I said at the start of this post - it is NOT a good idea to use the c_str() returned pointer. Always, always make a copy for a safer and better working programs :)

Best of luck!!