c++ - Difference in c_str function specification between C++03 and C++11 -

in c++ reference of c_str() in std::string following appears:

return value
pointer underlying character storage.
data()[i] == operator[](i) every in [0, size()) (until c++11)
data() + == &operator[](i) every in [0, size()] (since c++11)

i not understand difference between two, except range increase 1 element since c++11.

isn't former statement data()[i] == operator[](i) true latter?

except range increment 1 element since c++11, there still big difference between:

data()[i] == operator[](i) 

and:

data() + == &operator[](i) 

that main difference & operator in prototypes.

the old prototype, allowed copy made when write operation occur, since pointer returned point buffer 1 holding original string.

the other difference in prototypes between data()[i] , data() + i, not critical, since equivalent.

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a difference between c++ , c++11 in former, std::string not specified explicitly standard whether have null terminator or not. in latter however, specified.

in other words: will std::string null-terminated in c++11? yes.