C++ STL_vector 迭代器失效问题的解决方法

iterator insert(iterator pos, const T& x)
{
    assert(pos >= _start);
    assert(pos <= _finish);
    if (_finish == _endOfStorage)
    {
        size_t len = pos - _start;//先记下_start到pos位置的距离，因为扩容后迭代器pos就会失效
        reserve(capacity() == 0 ? 4 : 2 * capacity());
        pos = _start + len;//新的空间需要更新迭代器pos
    }
    iterator end = _finish - 1;
    //挪动数据
    while (end >= pos)
    {
        *(end + 1) = *end;
        --end;
    }
    *pos = x;
    ++_finish;
    return pos;
}

#include <iostream>
using namespace std;
#include <vector>
int main()
{
    int a[] = { 1, 2, 3, 4 };
    vector<int> v(a, a + sizeof(a) / sizeof(int));
    // 使用find查找3所在位置的iterator
    vector<int>::iterator pos = find(v.begin(), v.end(), 3);
    // 删除pos位置的数据，导致pos迭代器失效。
    v.erase(pos);
    cout << *pos << endl; // 此处会导致非法访问
    return 0;
}

iterator erase(iterator pos)
{
    assert(pos >= _start);
    assert(pos < _finish);
    iterator it = pos + 1;
    //挪动数据
    while (it < _endOfStorage)
    {
        *(it - 1) = *it;
        ++it;
    }
    --_finish;
    return pos;
}

int main()
{
    vector<int> v{1,2,3,4,5};
    for(size_t i = 0; i < v.size(); ++i)
    	cout << v[i] << " ";
    cout << endl;
    auto it = v.begin();
    cout << "扩容之前，vector的容量为: " << v.capacity() << endl;
    v.reserve(100);
    cout << "扩容之后，vector的容量为: " << v.capacity() << endl;
    while(it != v.end())
    {
        cout << *it << " ";
        ++it;
    }
    cout << endl;
    return 0;
}

#include <vector>
#include <algorithm>
using namespace std;
int main()
{
    vector<int> v{1,2,3,4,5};
    vector<int>::iterator it = find(v.begin(), v.end(), 3);
    v.erase(it);
    cout << *it << endl;
    while(it != v.end())
    {
        cout << *it << " ";
        ++it;
    }
    cout << endl;
    return 0;
}

int main()
{
	vector<int> v{1,2,3,4,5,6};
	auto it = v.begin();
	while (it != v.end())
	{
		if (*it % 2 == 0)
			v.erase(it);
		++it;
	}
	for (auto e : v)
		cout << e << " ";
	cout << endl;
	return 0;
}