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#ifndef VECTOR
#define VECTOR
template<typename T>
struct vector
{
private:
T *buffer;
unsigned long sz;
unsigned long cap;
public:
typedef T value_type;
typedef value_type& reference;
typedef const reference const_reference;
typedef value_type* pointer;
typedef const pointer const_pointer;
typedef T* iterator;
typedef const T* const_iterator;
typedef unsigned long size_type;
typedef ptrdiff_t difference_type;
vector() : buffer(new int[10]), sz(0), cap(10) {}
vector(size_t s) : buffer(new int[sz]), sz(s), cap(s){}
vector(size_t s, const T& initial) : buffer(new int[sz]), sz(s), cap(s) { for(size_t i = 0; i < sz; i++) buffer[i] = initial; }
template<typename container, typename It>
vector(typename container::It beg, typename container::It end)
{
It iter(beg);
sz = ptrdiff_t(beg-end);
cap = sz;
for(int i = 0; i < sz; i++)
{
buffer[i] = iter++;
}
}
~vector() {delete [] buffer;}
iterator begin() {return buffer;}
const_iterator begin() const {return buffer;}
iterator end() {return buffer+sz;}
const_iterator end() const {return buffer+sz;}
void reserve(size_t newCap)
{
if(newCap <= cap) return;
T *oldBuffer = buffer;
buffer = new T[newCap];
for(int i = 0; i < cap; i++)
{
buffer[i] = oldBuffer[i];
}
cap = newCap;
delete [] oldBuffer;
}
void resize(size_t newSz, const T& initial = T())
{
if(newSz > cap)
reserve((newSz*2+1)%(max_size()+1));
if(newSz > sz)
{
for(int i = sz; i < newSz; i++)
buffer[i] = initial;
}
sz = newSz;
}
size_t size() const {return sz;}
size_t capacity() const {return cap;}
bool empty() const {return sz == 0;}
size_t max_size() const {return 1073741823;}
void push_back(T toP)
{
if(sz >= cap)
reserve((cap*2+1)%(max_size()+1));
buffer[sz++] = toP;
}
T pop_back()
{
T ret = buffer[sz-1];
buffer[sz-1] = T();
sz--;
return ret;
}
reference front() { return buffer[0]; }
const_reference front() const { return buffer[0]; }
reference back() { return buffer[sz-1]; }
const_reference back() const { return buffer[sz-1]; }
T& operator[](size_t index) {if(index >= sz) throw std::out_of_range("out_of_rane"); return buffer[index]; }
const T& operator[] (size_t index) const {if(index >= sz) throw std::out_of_range("out_of_rane"); return buffer[index];}
T& at(size_t index) { return (*this)[index]; }
const T& at(size_t index) const { return (*this)[index]; }
};
#endif
這是vector類的實現。它使用T類型的動態數組,它隨着reserve()函數的增長而變大。如何使用分配器類來實現它? (全矢量類,而不僅僅是儲備功能)使用分配器類的矢量實現
template<class T, class Allocator = allocator<T> >
這是怎麼看起來像文件stl_vector.h
你問的是哪個版本更快/更高效,而沒有說明你的替代品是什麼。你已經給出了一個選項('template'')。我會假定從你提供的備選方案中選擇最快的一個... –
Grizzly
2012-04-18 15:09:00
包含雙下劃線的標識符(包括宏名稱),或者以下劃線開頭,後面跟着大寫字母,這些標識符是爲實現保留的。切勿在自己的代碼中使用它們。 – 2012-04-18 15:15:22
謝謝,我會記住它的。 – 2012-04-18 15:18:31