与 const std::string 的向量关联的编译失败

Question

请有人解释为什么以下代码不能使用 clang 3.5 编译。

报错是'No viable overloaded '='in algorithm.'

std::vector<const std::string> m_messages;
std::vector<const std::string>::iterator iter;
...

if (iter != m_messages.end())
{
    m_messages.erase(iter);      // compilation error
}

如果我将 m_messages 声明为：std::vector<std::string> m_messages; 则编译正常。

还有，有什么区别：

std::vector<const std::string> m_messages;

和

std::vector<std::string> m_messages;

TIA。

Answer 1

要擦除元素，必须重新定位右侧元素（向左移动）。

由于您的字符串是 const，旧元素无法被覆盖（通过 = 运算符）因此出现错误。

Answer 2

这是否意味着如果可以删除元素，则拥有 const 字符串向量没有意义？ Yes at least what the standard says

23.3.7.5 矢量修饰符[vector.modifiers]

iterator erase(const_iterator position); iterator erase(const_iterator first, const_iterator last);

Effects: Invalidates iterators and references at or after the point of the erase.

Complexity: The destructor of T is called the number of times equal to the number of the elements erased, but the move assignment operator of T is called the number of times equal to the number of elements in the vector after the erased elements.

Throws: Nothing unless an exception is thrown by the copy constructor, move constructor, assignment operator, or move assignment operator of T.

与 const std::string 的向量关联的编译失败

Compilation failure associated with vector of const std::string

c++

iterator

stdvector

c++11