C ++：为什么引入std :: vector :: data成员函数？

Question

I was looking at the STL's vector container from below link. And it is mentioned that one of the new member functions added (with C++11) to this container is vector::data , which returns a pointer to the memory array used internally.

http://www.cplusplus.com/reference/vector/vector/data/

The example code given in above link also shows it usage, but it seemed that all that could be done with iterators too.

Is there any specific reason for introduction of this member function?

Answer 1

from the comments:

• std::vector is a ContiguousContainer and can be accessed by pointers.
• access by pointer can be needed by C-like functions

There is potential for failure:

• deleting the pointer, will make the vecotr invalid and will create problems when the vector is destroyed.

• everything that leads to reallocation of the underlying data in vector (like adding elements or shrinking) will make the pointer to a dangling pointer. (As pointed out in the comments, this is also true for iterators and references)

Answer 2

I think the data() function was introduced for completeness of interface and convenience.

This way we do not need to resort to the ugliness of &vec[0] or &vec.front() .

Moreover, getting a pointer to the underlying data is useful in many applications, like interfacing with C code or some external libraries, or in embedded contexts for example.