string s1;
const char* p = s1.c_str();

after these, p seems to be a garbage pointer, and
cout << p[0]
output garbage and is reported as error by memory detection tool such
as purify.

Someone argue that either p has to be 0 or p[0] has to be '\0' for the
string calss, and the string class shouldn't give garbage for c_str()
for a string object initialized using 'string s1'.  Is this correct?

Thanks.


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Jianlin Chang wrote:

> string s1;
> const char* p = s1.c_str();
>
> after these, p seems to be a garbage pointer, and
> cout << p[0]
> output garbage and is reported as error by memory detection tool such
> as purify.
>
> Someone argue that either p has to be 0

I do not think that std::string::c_str() is allowed to return a null pointer
under any circumstances.

> or p[0] has to be '\0' for the
> string calss, and the string class shouldn't give garbage for c_str()
> for a string object initialized using 'string s1'.  Is this correct?

My understanding is that a string initialised by the default constructor
should have size() return zero. Under such circumstances, c_str() should
return a pointer to a null character in copyable memory.

So I would say that your implementation does not conform to the C++ standard
as I know it.


Alwyn



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string s1;

should create an empty string.

const char* p = s1.c_str();

p should be a valid pointer to an array of characters with a single null (0)
value.

Jianlin Chang wrote:

> string s1;
> const char* p = s1.c_str();
>
> after these, p seems to be a garbage pointer, and
> cout << p[0]
> output garbage and is reported as error by memory detection tool such
> as purify.
>
> Someone argue that either p has to be 0 or p[0] has to be '\0' for the
> string calss, and the string class shouldn't give garbage for c_str()
> for a string object initialized using 'string s1'.  Is this correct?

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