c++ - std::vector 元素是否保证是连续的？

Question

我的问题很简单:std::vector 元素是否保证是连续的？换句话说，我可以将指向 std::vector 的第一个元素的指针用作 C 数组吗？

如果我没记错的话，C++ 标准并没有做出这样的保证。但是，std::vector 要求是，如果元素不连续，几乎不可能满足这些要求。

有人可以澄清一下吗？

例子:

std::vector<int> values;
// ... fill up values

if( !values.empty() )
{
    int *array = &values[0];
    for( int i = 0; i < values.size(); ++i )
    {
        int v = array[i];
        // do something with 'v'
    }
}

Answer 1

这在 C++98 标准中被遗漏，但后来作为 TR 的一部分添加。即将发布的 C++0x 标准当然会包含这一要求。

来自 n2798(C++0x 草案):

23.2.6 Class template vector [vector]

1 A vector is a sequence container that supports random access iterators. In addition, it supports (amortized) constant time insert and erase operations at the end; insert and erase in the middle take linear time. Storage management is handled automatically, though hints can be given to improve efficiency. The elements of a vector are stored contiguously, meaning that if v is a vector where T is some type other than bool, then it obeys the identity &v[n] == &v[0] + n for all 0 <= n < v.size().