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Is std::string reference-counted when using gcc 4 with -std=c++0x or -std=c++11?
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The std::string class manages the underlying storage for you, storing your strings in a contiguous manner. You can get access to this underlying buffer using the c_str() member function, which will return a pointer to null-terminated char array. This allows std::string to interoperate with C-string APIs.
std::string actually maintains the size as one of its data member.
std::string class in C++ C++ has in its definition a way to represent a sequence of characters as an object of the class. This class is called std:: string. String class stores the characters as a sequence of bytes with the functionality of allowing access to the single-byte character.
Example. In below example for std::string::size. The size of str is 22 bytes.
Looking at libstdc++ documentation I find (see the link for more info):
A string looks like this:
[_Rep] _M_length [basic_string<char>] _M_capacity _M_dataplus _M_refcount _M_p ----------------> unnamed array of char_type So, yes it is ref counted. Also, from the discussion here:
Yes, std::string will be made non-reference counting at some point, but as a non-reference-counted string is valid in C++98 as well, one option would be to switch to a non-ref-counted string for both -std=c++98 and -std=c++11 modes. I'm not saying that's what will happen, but it could be.
So, it seems there are plans to change it to be conforming (I don't know how the progress is going though).
Update As emsr points out in the comments, there is currently a non-reference counted extension called vstring.h, and it seems the only reason it hasn't replaced std::string is because of ABI compatibility. There is an SO question about it here.
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C++11 added specific language forbidding std::string from being reference counted. So if it is, then it's a pretty significant failing in GCC's C++11 standard library.
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