c
复制代码
#pragma once
namespace My_vector
{
template<class T>
class vector
{
public:
typedef T* iterator; //typedef受访问限定符限制，要放成公有
typedef const T* const_iterator;
iterator begin()
{
return _start;
}
iterator end()
{
return _finish; //end和_finish都指向最后一个数的下一个
}
const_iterator begin() const
{
return _start;
}
const_iterator end() const
{
return _finish;
}
size_t capacity() const
{
return _endofstorage - _start;
}
size_t size() const
{
return _finish - _start;
}
//无参构造
vector()
:_start(nullptr)
, _finish(nullptr)
, _endofstorage(nullptr)
{}
//n个val值构造
vector(size_t n, const T val = T())
{
reserve(n);
for (size_t i = 0; i < n; i++)
{
push_back(val);
}
}
vector(int n, const T val = T())
{
reserve(n);
for (int i = 0; i < n; i++)
{
push_back(val);
}
}
//拷贝构造
vector(const vector<T>& v)
:_start(nullptr)
,_finish(nullptr)
,_endofstorage(nullptr)
{
reserve(v.capacity());
for (auto& e : v)
{
push_back(e);
}
}
//v3 = v1
void swap(vector<int>& v)
{
std::swap(_start, v._start);
std::swap(_finish, v._finish);
std::swap(_endofstorage, v._endofstorage);
}
vector<T>& operator=(vector<T> tmp) //传参用了拷贝构造
{
swap(tmp);
return *this;
}
//迭代区间构造
//类模板里可以套函数模板
template<class InputIterator>
vector(InputIterator first, InputIterator last)
:_start(nullptr)
, _finish(nullptr)
, _endofstorage(nullptr)
{
while (first != last)
{
push_back(*first);
++first;
}
}
~vector()
{
delete[] _start;
_start = _finish = _endofstorage = nullptr;
}
void reserve(size_t n)
{
size_t sz = size();
if (n > capacity())
{
T* tmp = new T[n];
if (_start)
{
//memcpy(tmp, _start, sizeof(T) * sz);
for (size_t i = 0; i < sz; i++)
{
tmp[i] = _start[i];
}
delete[] _start;
}
_start = tmp;
_finish = _start + sz;
_endofstorage = _start + n;
}
}
//void rsize(size_t n, T val = T())
void rsize(size_t n, const T& val = T()) //匿名对象具有常性，要加const
{
if (n > size())
{
reserve(n);
while (_finish < _start + n)
{
*_finish = val;
++_finish;
}
}
if (n <= size())
{
_finish = _start + n;
}
}
void push_back(const T& x)
{
if (_finish == _endofstorage)
{
/*size_t sz = size();
size_t cp = capacity() == 0 ? 4 : capacity() * 2;
T* tmp = new T[cp];
if (_start)
{
memcpy(tmp, _start, sizeof(T) * sz);
delete[] _start;
}
_start = tmp;
_finish = _start + sz;
_endofstorage = _start + cp;*/
reserve(capacity() == 0 ? 4 : capacity() * 2);
}
*_finish = x;
++_finish;
}
//insert、erase操作后迭代器都会失效，不能再访问
void insert(iterator pos, const T& x)
{
assert(pos >= _start);
assert(pos <= _finish);
if (_finish == _endofstorage)
{
size_t len = pos - _start;
reserve(capacity() == 0 ? 4 : capacity() * 2);
pos = _start + len; //扩容后要更新pos的相对位置
}
iterator end = _finish - 1;
while (end >= pos)
{
*(end + 1) = *end;
--end;
}
*pos = x;
++_finish;
}
iterator erase(iterator pos)
{
assert(pos >= _start);
assert(pos < _finish);
iterator it = pos + 1;
while (it < _finish)
{
*(it - 1) = *it;
it++;
}
--_finish;
return pos;
}
T& operator[](size_t pos)
{
assert(pos < size());
return _start[pos];
}
const T& operator[](size_t pos) const
{
assert(pos < size());
return _start[pos];
}
private:
iterator _start;
iterator _finish;
iterator _endofstorage;
};
void Test1()
{
vector<int> v;
v.push_back(1);
v.push_back(2);
v.push_back(3);
v.push_back(4);
v.push_back(5);
v.push_back(6);
for (size_t i = 0; i < v.size(); i++)
{
cout << v[i] << " ";
}
cout << endl;
vector<int>::iterator it = v.begin();
while (it != v.end())
{
*it *= 10;
cout << *it << ' ';
it++;
}
cout << endl;
for (auto e : v)
{
cout << e << " ";
}
cout << endl;
}
void Test2()
{
vector<int*> v1;
v1.rsize(5);
vector<string> v2;
//v2.rsize(5, string("xxx")); //匿名对象
v2.rsize(5, "xxx"); //隐式类型转换
for (auto e : v1)
{
cout << e << ' ';
}
cout << endl;
for (auto e : v2)
{
cout << e << ' ';
}
cout << endl;
}
void Test3()
{
vector<int> v;
v.push_back(1);
v.push_back(2);
v.push_back(3);
v.push_back(4);
v.push_back(5);
v.push_back(6);
for (auto e : v)
{
cout << e << ' ';
}
cout << endl;
v.insert(v.begin() + 2, 30);
v.insert(v.begin(), 0);
for (auto e : v)
{
cout << e << ' ';
}
cout << endl;
v.erase(v.begin());
v.erase(v.begin() + 2);
for (auto e : v)
{
cout << e << ' ';
}
cout << endl;
}
void Test4()
{
vector<int> v;
v.push_back(1);
v.push_back(2);
v.push_back(3);
v.push_back(4);
v.push_back(5);
v.push_back(6);
v.push_back(6);
v.push_back(7);
v.push_back(8);
auto it = v.begin();
while (it != v.end())
{
if (*it % 2 == 0)
{
it = v.erase(it);
//it = it - 1;
}
else
{
it++; //不删除再++
}
}
for (auto e : v)
{
cout << e << ' ';
}
cout << endl;
}
void Test5()
{
vector<string> v;
v.push_back("111111111111111111111");
v.push_back("111111111111111111111");
v.push_back("111111111111111111111");
v.push_back("111111111111111111111");
v.push_back("111111111111111111111");
for (auto e : v)
{
cout << e << " ";
}
cout << endl;
}
void Test6()
{
vector<int> v;
v.push_back(1);
v.push_back(2);
v.push_back(3);
v.push_back(4);
v.push_back(5);
for (auto e : v)
{
cout << e << " ";
}
cout << endl;
vector<int> v2(v);
for (auto e : v2)
{
cout << e << " ";
}
cout << endl;
vector<int> v3;
v3.push_back(3);
v3.push_back(4);
v3.push_back(5);
v3.push_back(6);
v3.push_back(7);
v2 = v3;
for (auto e : v2)
{
cout << e << " ";
}
cout << endl;
}
void Test7()
{
vector<int> v1(10, 15);
vector<int> v2(v1.begin(), v1.end());
for (auto e : v2)
{
cout << e << " ";
}
cout << endl;
vector<string> v3(5, "xxx");
vector<string> v4(v3.begin(), v3.end());
for (auto e : v4)
{
cout << e << " ";
}
cout << endl;
}
}
