Hi!
Actually I'm not quite sure about this, but I think you can assume that
this always works. I think what gets actually passed to printf is a
pointer to the value returned by c_str() which in turn is stored in some
independent temporary memory location until printf is done.
I use a lot of constructs like this and it always worked for me, (Intel
& GNU) however I might still be wrong. :)
Benjamin
On Wed, 2005-01-19 at 21:56 +0100, [EMAIL PROTECTED] wrote:
> Hi all,
>
> I have a function similar to the following, which returns a string:
>
> std::string foo() {
> return <whatever>;
> }
>
> ..then I want to use its c_str(), say like this (sorry for the silly
> example):
>
> int main() {
> printf("foo is %s",foo().c_str());
> }
>
> Of course, for printf() to work, the temporary object that is returned
> by foo() should not be (automatically) destroyed too early, or the
> pointer returned by c_str() would not be valid anymore.
>
> So, my question is: *when* is that temporary string created and
> destroyed? is it safe to assume that it exists until printf()
> returns, and thus that I can use its c_str() this way?
>
> I've always thought that the temporary would be destroyed *before*
> calling printf() [ create a string, get the value for c_str(),
> destroy the string, invoke printf() ] thus actually passing an
> invalid pointer in this case, but to my surprise I put together some
> lines and gcc proved me wrong. Is it just gcc? Or is it a standard
> C++ behavior?
>
> Thanks,
> Andrea.
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--
Benjamin Sobotta <[EMAIL PROTECTED]>
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