Assign part of a vector to itself using std::vector::assign()

Question

Let\'s say I have a vector(v1) of size 10. Now I want to only keep parts of the elements, using:
v1.assign(v1.begin() + 2, v1.begin() + 6);

What I\'

Answer 1

From the C++11 Standard:

23.3.6.2 vector constructors, copy, and assignment

template 
void assign(InputIterator first, InputIterator last);

11 Effects:

erase(begin(), end());
insert(begin(), first, last);

In other words, don't use:

v1.assign(v1.begin() + 2, v1.begin() + 6);

By the time insert is called, first will be an invalid iterator.