What's the difference between std::string::c_str and std::string::data? [duplicate]

Answer 1

c_str() guarantees NUL termination. data() does not.

Answer 2

Now in MS STL 10.0 there doesn't seem to be any difference, as I see this in the header:

...\Microsoft Visual Studio 10.0\VC\include\xstring

const _Elem *c_str() const
    {   // return pointer to null-terminated nonmutable array
    return (_Myptr());
    }

const _Elem *data() const
    {   // return pointer to nonmutable array
    return (c_str());
    }

So they return the same thing.

Answer 3

c_str() return a pointer to the data with a NUL byte appended so you can use the return value as a "C string".

data() returns a pointer to the data without any modifications.

Use c_str() if the code you are using assumes a string is NUL terminated (such as any function written to handle C strings).