Is it safe to return local CStringW to the caller?

Question

I have a function defined a local variable typed in CStringW, is it safe to return this object to the caller by value, not by reference?

The converse is actually what's not safe; don't return a reference to a local variable because when it gets out of scope your reference is dead. — GManNickG, Aug 10 '10 at 02:57

score 2 · Accepted Answer · answered Aug 10 '10 at 02:56

2

Yes, it should be ok. CString internally uses a buffer with reference counting and does copy-on-write, so that when you create a copy of CString and then destroy the original object, everything should "just work".

answered Aug 10 '10 at 02:56

Fyodor Soikin

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score 1 · Answer 2 · answered Aug 10 '10 at 02:58

I believe CString is from MFC, not STL, so you might want to change your tags.

If you're returning a local variable from a function, it's safe to return by value, but not safe to return by reference. Returning by value effectively copies the string to the caller. Returning by reference gives the caller a reference to the local variable which is destroyed when the function returns - so the caller can never use it, and the returned reference is always invalid.

Is it safe to return local CStringW to the caller?

2 Answers2