vector的模拟实现
- 模拟标准库中的·
vector
代码
my_vector.h
#pragma once
#include <iostream>
#include <assert.h>
using namespace std;
namespace my_vector
{
template<class T>
class vector
{
public:
typedef T* iterator;
typedef T* const_iterator;
vector()
{}
~vector()
{
delete[] _start;
_start = _finish=_endofstorage = nullptr;
}
vector(const vector<T>& x)
{
reserve(x.capacity());
for (auto& e : x)
{
push_back(e);
}
}
//vector<int> v = {1,2,3,4,5,6,7,8,9}
vector(initializer_list<T>il)
{
reserve(il.size());
for (auto& e : il)
{
push_back(e);
}
}
template <class InoutIterator>
vector(InoutIterator first, InoutIterator last)
{
while (first != last)
{
push_back(*first);
++first;
}
}
vector(size_t n, const T& val = T())
{
reserve(n);
for (size_t i = 0; i < n; i++)
{
push_back(val);
}
}
//防止 vector<int>v(10,1) 时冲突
vector(int n, const T& val = T())
{
reserve(n);
for (size_t i = 0; i < n; i++)
{
push_back(val);
}
}
vector<T>& operator=(vector<T> v)
{
swap(v);
return *this;
}
size_t size() const
{
return _finish - _start;
}
size_t capacity() const
{
return _endofstorage - _start;
}
void resize(size_t n,const T& val=T())
{
if (n < capacity())
{
_finish = _start + n;
}
else
{
reserve(n);
while (_finish < _start + n)
{
*_finish = val;
_finish++;
}
}
}
void reserve(size_t n)
{
if (n> capacity())
{
size_t old = size();
T* tmp = new T[n];
//memcpy(tmp, _start, size() * sizeof(T)); //T 为string时不能深拷贝
for (size_t i = 0; i < old; i++)
{
tmp[i] = _start[i];
}
delete[] _start;
_start = tmp;
_finish = _start + old;
_endofstorage = _start + n ;
}
else
{
_finish = _start + n;
}
}
void push_back(const T& val)
{
//判断容量
if (_finish == _endofstorage)
{
reserve(capacity() == 0 ? 4 : capacity() * 2);
}
*_finish = val;
++_finish;
}
void pop_back()
{
erase(end()-1);
}
iterator insert(iterator pos, const T& val)
{
assert(pos >= _start);
assert(pos <= _finish);
if (_finish == _endofstorage)
{
//记录pos位置
size_t len = pos - _start;
reserve(capacity() == 0 ? 4 : capacity() * 2);
//更新pos 如果不更新 迭代器会失效
pos = _start + len;
}
iterator it = _finish-1;
while (it >= pos)
{
*(it + 1) = *it;
--it;
}
*pos = val;
_finish++;
return pos;
}
iterator erase(iterator pos)
{
assert(pos >= _start);
assert(pos <= _finish);
if (empty())
return pos;
iterator it = pos;
while (it <= _finish)
{
*it = *(it + 1);
it++;
}
_finish--;
return pos;
}
iterator erase(iterator first, iterator last)
{
assert(first >= _start);
assert(first <= _finish);
size_t len = last - first;_finish-=(len);
if (empty())
return first;
if (last >= _finish)
{
_finish = first;
}
else
{
iterator it = first;
int i = 0;
while (it <= last)
{
*it = *(last+i);
i++;
it++;
}
while (it <= _finish)
{
*it = *(it + len);
it++;
}
}
return first;
}
bool empty()
{
return _start == _finish;
}
T& operator[] (size_t pos)
{
assert(pos < size());
return _start[pos];
}
const T& operator[] (size_t pos) const
{
assert(pos < size());
return _start[pos];
}
iterator begin()
{
return _start;
}
iterator end()
{
return _finish;
}
const_iterator begin() const
{
return _start;
}
const_iterator end() const
{
return _finish;
}
T& front()
{
return *begin();
}
const T& front() const
{
return *begin();
}
T& back()
{
return *(end() - 1);
}
const T& back() const
{
return *(end() - 1);
}
void clear()
{
_finish = _start;
}
void swap(vector<T>& x)
{
std::swap(_start, x._start);
std::swap(_finish, x._finish);
std::swap(_endofstorage, x._endofstorage);
}
private:
iterator _start=nullptr;
iterator _finish=nullptr;
iterator _endofstorage=nullptr;
};
template<typename T>
void print_vector(const vector<T>& v)
{
cout << "[]" << endl;
for (int i = 0; i < v.size(); i++)
{
cout << v[i] << ' ';
}
cout << endl;
typename vector<T>::iterator it = v.begin();
//auto it = v.begin();
cout << "iterator" << endl;
while (it != v.end())
{
cout << *it << ' ';
it++;
}
cout << endl;
cout << "autofor" << endl;
for (auto e : v)
{
cout << e << ' ';
}
cout << endl;
}
}