brad.power wrote:

> std::string s1 = "Hello, World";
> call_some_function(s1.c_str()); //Pass a const char* to some api
> m_stringvector.push_back(s1);
>
> Now, once s1 goes out of scope, it will destruct. I assume the copy of
> s1 sitting in the vector is exactly that - a copy. So the pointer
> value of the vectors s1.c_str() would be different to the local
> s1.c_str() (even though they would both contain the same string data).
> This means that once s1 goes out of scope, my c_str() array pointers
> that I have passed to external API's are invalid.

Can you positively determine this? Can you read the API's source, or its
documentation, or its tests?

Can you do this?

char yo[] = "hello world";
call_some_function(yo);
strcpy(yo, "bye-bye");

What string comes out the other end of this API? I don't know about other
programmers, but if I were writing a C API then I would take the Interface
part very seriously, and would not abuse pointers to things my clients
passed in.

> P.S. I tried to avoid threads, but the other api's I am working with
> need me to use them, or hang the UI while I do some long task.

In this case, you need to learn threading, and then use a semaphore to
ensure your thread-side objects live as long as the thread. And you need to
put your strings into a container (like your vector) which is itself a
member of these thread-side objects. Put the entire object onto the side of
your API - not just each danged string by itself.

And, are you absolutely certain your GUI will hang if you run the API? Does
it have any timer or semaphore system you can use to strobe your GUI?
Sometimes these systems are more robust...

--
Phlip
http://www.oreilly.com/catalog/9780596510657/
"Test Driven Ajax (on Rails)"
assert_xpath, assert_javascript, & assert_ajax