目录
一、vector的基本实现机制：
namespace ppr
{
template<class T>
class vector
{
public:
typedef T* iterator;
typedef const T* const_iterator;
iterator begin()
{
return _start;
}
iterator end()
{
return _finish;
}
const_iterator begin() const
{
return _start;
}
const_iterator end() const
{
return _finish;
}
size_t size() const
{
return _finish - _start;
}
size_t capacity() const
{
return _endofstorage - _start;
}
private:
iterator _start;
iterator _finish;
iterator _endofstorage;
};二、vector的部分接口模拟实现：
1、构造与析构：
1、普通构造：
vector()
:_start(nullptr)
, _finish(nullptr)
, _endofstorage(nullptr)
{}2、拷贝构造：
vector(const vector<T>& v)
:_start(nullptr)
, _finish(nullptr)
, _endofstorage(nullptr)
{
_start = new T[v.capacity()];
memcpy(_start, v._start.sizeof(T) * v.size());
_finish = _start + v.size();
_endofstorage = _start + v.capacity();
}3、析构函数：
~vector()
{
if (_start != nullptr)
{
delete[] _start;
_start = _finish = _endofstorage = nullptr;
}
}2、关于扩容：
1、reserve：
void reserve(size_t n)
{
size_t sz = size();
if (n > capacity())
{
T* tmp = new T[n];
if (_start != nullptr)
{
memcpy(tmp, _start, sizeof(T) * sz);
delete[] _start;
}
_start = tmp;
_finish = _start + sz;
_endofstorage = _start + n;
}
}
2、resize
void resize(size_t n,const T& val = T())
{
if (n < size())
{
_finish = _start + n;
}
else
{
reserve(n);
while (_finish != _start + n)
{
*_finish = val;
_finish++;
}
}
}3、增删查改：
1、在pos位置插入：
iterator insert(iterator pos ,const T& x)
{
assert(pos >= _start && pos <= _finish);
if (_finish == _endofstorage)
{
size_t len = pos - _start;
size_t newcapacity = capacity() == 0 ? 4 : capacity() * 2;
reserve(newcapacity);
pos = _start + len;
}
iterator end = _finish - 1;
while (end >= pos)
{
*(end + 1) = *end;
--end;
}
*pos = x;
_finish++;
return pos;
}2、[]符号访问修改：
T& operator[](size_t pos)
{
assert(pos<size());
return _start[pos];
}
const T& operator[](size_t pos) const
{
assert(pos < size());
return _start[pos];
}3、删除pos位置的值：
iterator erase(iterator pos)
{
assert(pos >= _start && pos < _finish);
iterator it = pos + 1;
while (it != _finish)
{
*(it - 1) = *it;
++it;
}
--_finish;
return pos;
}4、重载=运算符：
void swap(vector<T>& v)
{
std::swap(_start, v._start);
std::swap(_finish, v._finish);
std::swap(_endofstorage, v._endofstorage);
}
vector<T>& operator=(vector<T> v)
{
swap(v);
return *this;
}
