Vector vs string

Question

What is the fundamental difference, if any, between a C++ std::vector and std::basic_string?

Answer 1

• basic_string doesn't call constructors and destructors of its elements. vector does.

• swapping basic_string invalidates iterators (enabling small string optimization), swapping vectors doesn't.

• basic_string memory may not be allocated continuously in C++03. vector is always continuous. This difference is removed in C++0x [string.require]:

  The char-like objects in a basic_string object shall be stored contiguously

• basic_string has interface for string operations. vector doesn't.

• basic_string may use copy on write strategy (in pre C++11). vector can't.

Relevant quotes for non-believers:

[basic.string]:

The class template basic_string conforms to the requirements for a Sequence Container (23.2.3), for a Reversible Container (23.2), and for an Allocator-aware container (Table 99), except that basic_string does not construct or destroy its elements using allocator_traits::construct and allocator_- traits::destroy and that swap() for basic_string invalidates iterators. The iterators supported by basic_string are random access iterators (24.2.7).