std::ostringstream to LPCSTR?

Question

How can I convert a std::ostringstream to LPCSTR?

std::ostringstream oss;
[...]
LPCSTR result = oss.str();

Result: Error: No suitable conversion function from "std::basic_string<char, std::char_traits<char>, std::allocator<char>>" to "LPCSTR" exists

David Heffernan · Accepted Answer · 2015-08-18T10:58:52.863

7

Like this:

std::string str = oss.str();
LPCSTR cstr = str.c_str();

Note that you cstr only remains valid until the next modification of str. So you cannot, for instance, return cstr from a function because str is a local variable that has left scope.

Instead of returning LPCSTR from this function, return std::string. That avoids dealing with lifetime issues if you returned LPCSTR. If you returned LPCSTR you would have to allocate memory and make sure you deallocated it. Exactly the sort of thing you don't want to be doing in C++ code. So, return std::string and call c_str() on that object at the point where you call the Windows API function.

edited Aug 18 '15 at 10:58

answered Aug 18 '15 at 10:46

David Heffernan

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Returning it was exactly what I was planning to do, so how could I do that? – Tom Doodler Aug 18 '15 at 10:50
Don't do that. It will leave you with all sorts of lifetime headaches. Return a `std::string` and call `c_str()` on that at the point where you need to call the winapi function. – David Heffernan Aug 18 '15 at 10:54
1

Returning a reference to a local isn't going to end well. Don't hand out dead cows (or objects in general). – IInspectable Aug 18 '15 at 10:58
@IInspectable Sorry, you are quite right. Comment and answer edited. – David Heffernan Aug 18 '15 at 10:59

std::ostringstream to LPCSTR?

1 Answers1