构造函数声明 | 接口说明 |
---|---|
vector() | 无参构造 |
vector(size_type n, const value_type& val = value_type()) | 构造并初始化n个val |
vector (const vector& x); | 拷贝构造 |
vector (InputIterator first, InputIterator last); | 使用迭代器进行初始化构造 |
#include<iostream>
#include<vector>
using namespace std;
int main()
{
vector<int> a;
vector<int> b(6, 10);
vector<int> c(b);
vector<int> d(c.begin(), c.end());
for (int i = 0; i < a.size(); i++)
cout << a[i] << " ";
cout << endl;
for (int i = 0; i < b.size(); i++)
cout << b[i] << " ";
cout << endl;
for (int i = 0; i < c.size(); i++)
cout << c[i] << " ";
cout << endl;
for (int i = 0; i < d.size(); i++)
cout << d[i] << " ";
cout << endl;
int e[] = { 3, 43, 2, 3435, 2, 65, 7, 8, 2, 7, 54 };
vector<int> f(e, e + sizeof(e) / sizeof(e[0]));
for (int i = 0; i < f.size(); i++)
cout << f[i] << " ";
cout << endl;
system("pause");
return 0;
}
iterator的使用 | 接口说明 |
---|---|
begin() | 获取第一个数据位置的iterator |
end() | 获取最后一个数据的下一个位置的iterator |
rbegin() | 获取最后一个数据位置的reverse_iterator |
rend() | 获取第一个数据前一个位置的reverse_iterator |
cbegin() | 获取第一个数据位置的const_iterator |
cend() | 获取最后一个数据的下一个位置的const_iterator |
#include<iostream>
#include<vector>
using namespace std;
int main()
{
vector<int> ans;
ans.push_back(1);
ans.push_back(2);
ans.push_back(3);
ans.push_back(4);
ans.push_back(5);
//使用迭代器进行遍历
vector<int>::iterator it = ans.begin();
while (it != ans.end())
{
cout << *it << " ";
it++;
}
cout << endl;
//使用迭代器进行修改
it = ans.begin();
while (it != ans.end())
{
*it=*it * 2;
it++;
}
for (int i = 0; i < ans.size(); i++)
cout << ans[i] << " ";
cout << endl;
//使用逆向迭代器进行迭代
vector<int>::reverse_iterator rit = ans.rbegin();
while (rit != ans.rend())
{
cout << *rit << " ";
rit++;
}
cout << endl;
system("pause");
return 0;
}
容量空间 | 接口说明 |
---|---|
size() | 获取数据个数 |
capacity() | 获取容量大小 |
empty() | 判断是否为空 |
void resize (size_type n, value_type val = value_type()); | 改变vector的size |
void reserve (size_type n); | 改变vector放入capacity |
#include<iostream>
#include<vector>
using namespace std;
int main()
{
vector<int> ans;
int sz = ans.capacity();
for (int i = 0; i < 100; i++)
{
ans.push_back(i);
if (sz != ans.capacity()) {
sz = ans.capacity();
std::cout << "capacity changed: " << sz << '\n';
}
}
system("pause");
return 0;
}
vector增删查改 | 接口说明 |
---|---|
void push_back (const value_type& val); | 尾插 |
void pop_back(); | 尾删 |
InputIterator find (InputIterator first, InputIterator last, const T& val); | 查找。(注意这个是算法模块实现,不是vector的成员接口) |
iterator insert (iterator position, const value_type& val); | 在position之前插入val |
iterator erase (iterator position); | 删除position位置的数据 |
void swap (vector& x); | 交换两个vector的数据空间 |
reference operator[] (size_type n); | 像数组一样访问 |
#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int main()
{
vector<int> ans;
ans.push_back(1);
ans.push_back(2);
ans.push_back(3);
ans.push_back(4);
ans.push_back(5);
//删除尾部
ans.pop_back();
//使用迭代器查找
vector<int>::iterator it = find(ans.begin(), ans.end(), 3);
//插入
ans.insert(it, 50);
//使用迭代器遍历
it = ans.begin();
while (it != ans.end()) {
cout << *it << " ";
++it;
}
cout << endl;
system("pause");
return 0;
}
#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
int main()
{
int a[] = { 1, 2, 3, 4 };
vector<int> v(a, a + sizeof(a) / sizeof(int));
// 使用find查找3所在位置的iterator
vector<int>::iterator pos = find(v.begin(), v.end(), 3);
// 删除pos位置的数据,导致pos迭代器失效。
v.erase(pos);
cout << *pos << endl; // 此处会导致非法访问
// 在pos位置插入数据,导致pos迭代器失效。
// insert会导致迭代器失效,是因为insert可
// 能会导致增容,增容后pos还指向原来的空间,而原来的空间已经释放了。
pos = find(v.begin(), v.end(), 3);
v.insert(pos, 30);
cout << *pos << endl; // 此处会导致非法访问
return 0;
}
#include<iostream>
#include<string>
#include<assert.h>
using namespace std;
namespace fxl
{
template<class T>
class vector
{
public:
typedef T* Iterator;
typedef const T* ConstIterator;
Iterator Begin(){ return _start; }
Iterator End(){ return _finish; }
ConstIterator CBegin(){ return _start; }
ConstIterator CEnd(){ return _finish; }
size_t Size(){ return _finish - _start; }
size_t Capacity(){ return _endOfStorage - _start; }
vector()
:_start=nullptr
,_finish=nullptr
,_endOfStorage=nullptr
{}
vector(int n, const T& value = T())
:_start=nullptr
,_finish=nullptr
,_endOfStorage=nullptr
{
Reserve(n);
while (n--)
{
Push_Back(value);
}
}
template<class InputIterator>
Vector(InputIterator first, InputIterator last)
{
Reserve(last - first);
while (first!=last)
{
Push_Back(*first);
first++:
}
}
vector(const vector<T>& v)
:_start=nullptr
,_finish=nullptr
,_endOfStorage=nullptr
{
Reserve(v.Capacity());
Iterator it = Begin();
const vit = v.CBegin();
while (vit != v.CEnd())
{
*it++ = *vit++;
}
_finish = _start + v.Size();
_endOfStorage = _start + v.Capacity();
}
vector<T>& operator= (vector<T> v)
{
swap(v);
return *this;
}
~vector()
{
delete[] _start;
_start = _finish = _endOfStorage = nullptr;
}
void Reserve(size_t n)
{
if (n > Capacity())
{
size_t size = Size();
T tmp = new T[n];
if (_start)
{
for (size_t i = 0; i < size; ++i)
tmp[i] = _start[i];
}
_start = tmp;
_finish = _start + size;
_endOfStorage = _start + n;
}
}
void Resize(size_t n, const T& value = T())
{
if (n < Capacity())
{
_finish = _start + n;
return;
}
else
{
Reserve(n);
}
Iterator it = _finish;
Iterator _finish = _start + n;
while (it != _finish)
{
*it++ = value;
}
}
void Swap(Vector<T>& v)
{
swap(_start, v._start);
swap(_finish, v._finish);
swap(_endOfStorage, v._endOfStorage);
}
void PushBack(const T& x)
{
Insert(End(), x);
}
void PopBack()
{
Erase(--End());
}
Iterator Insert(Iterator pos, const T& x)
{
assert(pos <= _finish);
//如果空间不足就增容
if (_finish == _endOfStorage)
{
size_t size = Size();
size_t newCapacity = Capacity == 0 ? 1 : Capacity() * 2;
Reserve(newCapacity);
//如果发生增容,需要重置pos
pos = _start + size;
}
Iterator end = _finish - 1;
while (end >= pos)
{
*(end + 1) = *end;
--end;
}
*pos = x;
++_finish;
return pos;
}
Iterator Erase(Iterator pos)
{
// 挪动数据进行删除
Iterator begin = pos + 1;
while (begin != _finish) {
*(begin - 1) = *begin;
++begin;
}
--_finish;
return pos;
}
T& operator[](size_t pos)
{
return _start[pos];
}
private:
Iterator _start; // 指向数据块的开始
Iterator _finish; // 指向有效数据的尾
Iterator _endOfStorage;
};
}