我正在尝试在 cpp 中重新创建内置向量类，以便在类和内存管理方面进行更多练习。我不断收到一条错误消息，上面写着“ISO C++ 禁止声明没有类型的'分配器'”，我无法弄清楚为什么会这样。有什么我想念的吗？
#include <cstddef>
#include <memory>
template <class T>
class myvector{
public:
typedef T* iterator;
typedef const T* const_iterator;
typedef size_t size_type;
myvector(){ data = avail = limit = 0; }
explicit myvector(size_type n, const T& t = T()) { create(n,t); }
myvector(const myvector& v){ create(v.begin(), v.end()); }
~myvector() { uncreate(); }
myvector& operator=(const myvector& v)
{
if (&v != this){
uncreate();
create(v.begin(), v.end());
}
return *this;
}
T& operator[](size_type i) { return data[i]; }
const T& operator[](size_type i) const { return data[i]; }
iterator begin(){ return data; }
const_iterator begin() const{ return data; }
iterator end(){ return limit; }
const_iterator end() const{ return limit; }
size_type size(){ return avail - data; }
void push_back(T t)
{
if(avail == limit)
size_type new_size = max(2*(limit-data),ptrdiff_t(1));
iterator new_data = alloc.allocate(new_size);
iterator new_avail = uninitialized_copy(data,avail,new_data);
uncreate();
data = new_data;
avail = new_avail;
limit = data + new_size;
alloc.construct(avail++,t);
}
private:
iterator data;
iterator avail;
iterator limit;
allocator<T> alloc;
void create(size_type n, const T& t)
{
data = alloc.allocate(n);
limit = avail = data+n;
uninitialized_fill(data,limit,t);
}
void create(const_iterator i, const_iterator j)
{
data = alloc.allocate(j-i);
limit = avail = uninitialized_copy(i,j,data);
}
void uncreate()
{
if(data){
iterator it = avail;
while(it != data) { alloc.destroy(--it); }
alloc.deallocate(data,limit-data);
}
data = limit = avail = 0;
}
};