注意幾點(diǎn)：
分配內(nèi)存不要使用new和delete，因?yàn)閚ew的同時(shí)就把對象構(gòu)造了，而我們需要的是原始內(nèi)存。所以應(yīng)該使用標(biāo)準(zhǔn)庫提供的allocator類來實(shí)現(xiàn)內(nèi)存的控制。當(dāng)然也可以重載operator new操作符，因?yàn)槎叨际鞘褂胢alloc作為底層實(shí)現(xiàn)，所以直接采用malloc也可以。
對象的復(fù)制必須使用系統(tǒng)提供的uninitialized_fill和uninitialized_copy，因?yàn)槲覀儫o法手工調(diào)用構(gòu)造函數(shù)。
對于C++中的對象，除了POD之外，使用memcpy系列的函數(shù)是絕對錯(cuò)誤的。
myvector.h
#ifndef _VECTOR_H_
#define _VECTOR_H_
#include <stddef.h>
#include <algorithm>
#include <memory>
template <typename T>
class Vector
{
public:
typedef T *iterator;
typedef const T *const_iterator;
typedef size_t size_type;
typedef T value_type;
class reverse_iterator
{
public:
reverse_iterator(iterator it = NULL):current_(it) {}
iterator base() const { return current_; }
reverse_iterator &operator++()//前置
{
--current_;
return *this;
}
reverse_iterator operator++(int)//后置
{
reverse_iterator temp(*this);
--current_;
return temp;
}
reverse_iterator &operator--()
{
++current_;
return *this;
}
reverse_iterator operator--(int)
{
reverse_iterator temp(*this);
++current_;
return temp;
}
T &operator*()
{
iterator temp = current_;
return *--temp;
}
T *operator->()
{
iterator temp = current_;
return --temp;
}
friend bool operator==(const reverse_iterator &lhs,
const reverse_iterator &rhs)
{
return lhs.current_ == rhs.current_;
}
friend bool operator!=(const reverse_iterator &lhs,
const reverse_iterator &rhs)
{
return lhs.current_ != rhs.current_;
}
private:
iterator current_;
};
Vector() { create(); }//無參構(gòu)造函數(shù)
explicit Vector(size_type n, const T &t = T()) { create(n, t); }
Vector(const Vector &v) { create(v.begin(), v.end());}// 拷貝構(gòu)造函數(shù)
~Vector() { uncreate();}
Vector &operator=(const Vector &other);
T &operator[] (size_type i) { return data_[i]; }
const T &operator[] (size_type i) const {return data_[i]; }
void push_back(const T &t);
size_type size() const { return avail_ - data_;}
size_type capacity()const { return limit_ - data_;}
iterator begin() { return data_; }
const_iterator begin() const {return data_;}
iterator end() {return avail_;}
const_iterator end() const { return avail_; }
reverse_iterator rbegin(){return reverse_iterator(end());}
reverse_iterator rend() {return reverse_iterator(begin());}
void swap(Vector &rhs)
{
std::swap(data_, rhs.data_);
std::swap(avail_, rhs.avail_);
std::swap(limit_, rhs.limit_);
}
private:
iterator data_;//首元素
iterator avail_;//末尾元素的下一個(gè)
iterator limit_;
std::allocator<T> alloc_;//內(nèi)存分配器
void create();
void create(size_type, const T &);
void create(const_iterator, const_iterator);
void uncreate();
void grow();
void uncheckAppend(const T &);
};
template <typename T>
inline Vector<T> &Vector<T>::operator=(const Vector &rhs)
{
if(this != rhs)
{
uncreate();//釋放原來的內(nèi)存
create(rhs.begin(), rhs.end());
}
return *this;
}
template <typename T>
inline void Vector<T>::push_back(const T &t)
{
if(avail_ == limit_)
{
grow();
}
uncheckAppend(t);
}
template <typename T>
inline void Vector<T>::create()
{
//分配空的數(shù)組
data_ = avail_ = limit_ = 0;
}
template <typename T>
inline void Vector<T>::create(size_type n, const T &val)
{
//分配原始內(nèi)存
data_ = alloc_.allocate(n);
limit_ = avail_ = data_ + n;
//向原始內(nèi)存填充元素
std::uninitialized_fill(data_, limit_, val);
}
template <typename T>
inline void Vector<T>::create(const_iterator i, const_iterator j)
{
data_ = alloc_.allocate(j-i);
limit_ = avail_ = std::uninitialized_copy(i, j, data_);
}
template <typename T>
inline void Vector<T>::uncreate()
{
if(data_)//逐個(gè)析構(gòu)
{
iterator it = avail_;
while(it != data_)
{
alloc_.destroy(--it);
}
alloc_.deallocate(data_, limit_ - data_ );//真正釋放內(nèi)存
}
data_ = limit_ = avail_ = 0;//重置指針
}
template <typename T>
inline void Vector<T>::grow()
{
//內(nèi)存變?yōu)?倍
size_type new_size = std::max(2 * (limit_ - data_), std::ptrdiff_t(1));
//分配原始內(nèi)存
iterator new_data = alloc_.allocate(new_size);
//復(fù)制元素
iterator new_avail = std::uninitialized_copy(data_, avail_, new_data);
uncreate();//釋放以前內(nèi)存
data_ = new_data;
avail_ = new_avail;
limit_ = data_ + new_size;
}
template <typename T>
inline void Vector<T>::uncheckAppend(const T &val)
{
alloc_.construct(avail_++, val);
}
#endif /*VECTOR_H*/
test_main.cpp
#include "myvector.h"
#include <iostream>
#include <string>
using namespace std;
void print_reverse(Vector<string> &vec)
{
cout << "reverse_iterator: " << endl;
for(Vector<string>::reverse_iterator it = vec.rbegin();
it != vec.rend();
++it)
{
cout << *it << endl;
}
cout << endl;
}
void print(Vector<string> &vec)
{
cout << "iterator: " << endl;
for(Vector<string>::iterator it = vec.begin();
it != vec.end();
++it)
{
cout << *it << endl;
}
cout << endl;
}
int main(int argc, const char *argv[])
{
Vector<string> vec(3, "hello");
for(Vector<string>::const_iterator it = vec.begin();
it != vec.end();
++it)
{
cout << *it << endl;
}
cout << endl;
cout << "size=" << vec.size() << endl;
cout << "capacity:" << vec.capacity() << endl;
vec.push_back("foo");
vec.push_back("bar");
cout << "size:=" << vec.size() << endl;
cout << "capacity=" << vec.capacity() << endl;
print_reverse(vec);
print(vec);
return 0;
}
《C++ 設(shè)計(jì)新思維》 下載見 http://www.linuxidc.com/Linux/2014-07/104850.htm
C++ Primer Plus 第6版 中文版 清晰有書簽PDF+源代碼 http://www.linuxidc.com/Linux/2014-05/101227.htm
讀C++ Primer 之構(gòu)造函數(shù)陷阱 http://www.linuxidc.com/Linux/2011-08/40176.htm
讀C++ Primer 之智能指針 http://www.linuxidc.com/Linux/2011-08/40177.htm
讀C++ Primer 之句柄類 http://www.linuxidc.com/Linux/2011-08/40175.htm
將C語言梳理一下，分布在以下10個(gè)章節(jié)中：
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