擦除获取const_iterator，但通过迭代器调用（非const）

Question

In C++11 std::vector::erase gets as first argument const_iterator (older one was with iterator):

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

But as you can see in the example it uses with not cbegin . Instead it uses with begin . Is there an implicit conversion between const_iterator and iterator ?

Answer 1

The requirement on containers is that iterator type must be implcitly convertible to const_iterator .

See: http://en.cppreference.com/w/cpp/concept/Container

So, something like below will work:

std::vector<int> v;
.....
std::vector<int>::const_iterator cit = v.begin();

Answer 2

Yes, iterator of std containers is (and must be) convertible to const_iterator .

From the standard, $23.2.1/4 General container requirements [container.requirements.general] Table 100 — Container requirements :

(Emphasis mine)

X::iterator

any iterator category that meets the forward iterator requirements. convertible to X::const_iterator .