Is std::string terminated with '/0'?

Question

char *pt = "hello";
std::string str = "hello";

Does str also end with '/0' (is null terminated)?

maybe? `str.data()` will give you null terminated c string, aside from that you don't really care. — yngccc, Nov 28 '13 at 00:51
This question doesn't quite make sense as-is. `std::string` is neither an array nor a pointer, it's a class. How would you define what it "ends with"? — , Nov 28 '13 at 00:51
The accepted answer of that question doesn't state that it must be null terminated (or even contiguous?!), but neither here or there do we see quotes from the C++ spec. — Prashant Kumar, Nov 28 '13 at 00:57

score 3 · Answer 1 · edited Nov 29 '13 at 05:52

3

It is implementation defined whether or not std::string is null-terminated.

The actual contents of str after its definition:

std::string str = "hello";

are characters 'h', 'e', 'l', 'l', 'o' and its size is equal only to 5 characters.

edited Nov 29 '13 at 05:52

Prashant Kumar

answered Nov 28 '13 at 00:55

Vlad from Moscow

While this is true, the standard also requires that the underlying controlled sequence be zero terminated when you access it via either `c_str`, `data` or `operator[]` member functions. – Praetorian Nov 28 '13 at 01:04
do you make sure that str isn't end with '\o' – jiafu Nov 28 '13 at 03:04

score 2 · Answer 2 · edited Nov 28 '13 at 00:59

2

The buffer manged by str MAY be null terminated, but not necessarily.

edited Nov 28 '13 at 00:59

Shoe

answered Nov 28 '13 at 00:51

Bukes

2

Actually, as I reckon, C++(11?) requires `&str[0]` to point to `str.c_str()`. – Nov 28 '13 at 00:53
1

@H2CO3 That is indeed the case with C++11. Not so much with previous versions, however. – Etienne de Martel Nov 28 '13 at 00:56

score 0 · Answer 3 · answered Nov 28 '13 at 01:10

str.c_str() will provide you a const char*, which pointed to a null-terminated, contiguous buffer (like your "hello" string literal was).

But be aware of using &str[0] because it's not guaranteed that this points to a contiguous buffer, neither that this buffer is null-terminated.

3 Answers3