C++实现动态顺序表（vector）

vector是连续存储结构，支持随机的高效的随机和在尾部进行插入、删除操作，其它位置的插入、删除操作相对来说效率较低。
vector相当于一个数组，但它的数组空间大小需要写一程序来实现。
它的内存分配原理大概可分为下面几步：
1）首先分配一块内存空间进行存储；
2）当所需存储的数据超过分配的空间时，再重新分配一块空间；
3）将旧元素复制到新空间；
4）释放旧空间。

实现代码如下：

vector.h

#pragma once

#include
#include
#include
#include
using namespace std;

typedef int DataType;

class Vector
{
public:
    Vector()
        :_first(NULL),
        _finish(NULL),
        _endofstorage(NULL)
    {}

    Vector(const Vector& v){
        if (v.Size() > 0){
            _first = new DataType(v.Size());
            memcpy(_first, v._first, sizeof (DataType)*v.Size());
        }
        if (_first > 0){
            _finish = _first + v.Size();
            _endofstorage = _first + v.Size();
        }
        _first = _finish = _endofstorage = NULL;
    }

    Vector& operator=(const Vector& v){
        if (this != &v){
            /*swap(_first, v._first);
            swap(_finish, v._finish);
            swap(_endofstorage, v._endofstorage);*/

            DataType* tmp = new DataType(v.Size());
            memcpy(tmp, _first, sizeof(DataType)*v.Size());
            delete _first;
            _first = tmp;
            _finish = _first + v.Size();
            _endofstorage = _first + v.Size();
        }
        return *this;
    }

    ~Vector(){
        delete[] _first;
        _first = _finish = _endofstorage = NULL;
    }

    void Print(){
        DataType* cur = _first;
        while (cur != _first){
            cout << "*cur" << endl;
            cur++;
        }
        cout << endl;
    }

    size_t Size() const{
        return _finish - _first;
    }

    size_t Capacity() const{
        return _endofstorage - _first;
    }

    void Expand(size_t n){
        if (n > Capacity()){
            DataType* tmp = new DataType(n);
            size_t size = Size();
            memcpy(tmp, _first, sizeof(DataType)*size);
            delete[] _first;
            _first = tmp;
            _finish = _first + size;
            _endofstorage = _first + n;
        }
    }

    void PushBack(DataType x){
        if (_finish == _endofstorage){
            size_t capacity = Capacity() > 0 ? Capacity() * 2 : 3;
            Expand(capacity);
            /*if (Capacity() == 0){
                Expand(3);
            }
            else{
                Expand(Capacity() * 2);
            }*/
        }
        *_finish = x;
        ++_finish;
    }

    void PopBack(){
        assert(_finish > _first);
        --_finish;
    }

    void Reserve(size_t n){
        if (n > Capacity()){
            Expand(n);
        }
    }

    void Insert(size_t pos, DataType x){
        assert(pos < Size());
        if (_finish = _endofstorage){
            size_t capacity = Capacity() > 0 ? Capacity() * 2 : 3;
            Expand(capacity);
        }
        int tmp = Size() - 1;
        while (tmp >= (int)pos){
            _first[tmp + 1] = _first[tmp];
            --tmp;
        }
        _first[pos] = x;
        ++_finish;
    }

    void Erase(size_t pos){
        assert(pos < Size());
        size_t cur = pos;
        while (cur < Size()-1){
            _first[cur] = _first[cur] + 1;
            ++cur; 
        }
        --_finish;
    }

    size_t Find(DataType x){
        DataType *cur = _first;
        while (cur != _finish){
            if (*cur == x){
                return cur - _first;
            }
            ++cur;
        }
        return -1;
    }
private:
    DataType* _first;
    DataType* _finish;
    DataType* _endofstorage;
};

test.cpp

#include"vector.h"

void Tset(){
    Vector v;
    v.PushBack(1);
    v.PushBack(2);
    v.PushBack(3);
    v.PushBack(4);
    v.PopBack();
    v.Print();

    size_t pos = v.Find(1);
    printf("pos->data:expcet 1,axtual %lu", pos);

    Vector v1;
    v1.Insert(1, 0);
    v1.Print();

    Vector v2;
    v2.Erase(3);
    v2.Print();
}

int main(){
    Tset();
    return 0;
}