如何使用向量作为基类

Win7Cygwin

这是我第一次使用模板&集装箱。我不明白这些错误。对于我（天真的）看待事物的方式，我定义了一个分配器（_Alloc）和一个typdef（分配器类型）。这些信息似乎是在说我没有做好家庭作业。我不知道该怎么办。

代码为：

template<typename T, typename _Alloc = std::allocator<T>>
class Array : public vector<T, _Alloc> {
   public:
      typedef T         value_type;
      typedef _Alloc    allocator_Type;
   private:
   int compar (const void* p1, const void* p2) { T v1 = (T)*p1;
                                                 T v2 = (T)*p2;
                                                 return (v1 < v2)? -1: (v1 > v2)? 1: 0;   }
   public:
   explicit Array (const allocator_Type& alloc = allocator_type()) : vector<T, _Alloc>(alloc)    { };
   explicit Array (size_t n)                                       : vector<T, _Alloc>(n)        { };
            Array (size_t n, const T& val,
                    const allocator_type& alloc = allocator_type()): vector<T, _Alloc>(n, val, alloc) { };
};

错误消息为：

main.cpp:31:27: error: 'allocator_type' does not name a type
                     const allocator_type& alloc = allocator_type()): vector<T, _Alloc>(n, val, alloc) { };
                           ^
main.cpp:31:27: note: (perhaps 'typename std::vector<_Tp, _Alloc>::allocator_type' was intended)
main.cpp:31:66: warning: ISO C++ forbids declaration of 'alloc' with no type [-fpermissive]
                     const allocator_type& alloc = allocator_type()): vector<T, _Alloc>(n, val, alloc) { };
                                                                  ^
main.cpp:28:65: warning: there are no arguments to 'allocator_type' that depend on a template parameter, so a declaration of 'allocator_type' must be available [-fpermissive]
    explicit Array (const allocator_Type& alloc = allocator_type()) : vector<T, _Alloc>(alloc)    { };
                                                                 ^
main.cpp:31:66: warning: there are no arguments to 'allocator_type' that depend on a template parameter, so a declaration of 'allocator_type' must be available [-fpermissive]
                     const allocator_type& alloc = allocator_type()): vector<T, _Alloc>(n, val, alloc) { };
                                                                  ^