22081

22081

1、仿照系统的vector，手动实现一个my_vector

#include <iostream>using namespace std;
template<typename T>
class myvect
{
private:T* start;//起始指针T* last;//数组有效长度的尾指针T* end;//数组末尾的尾指针
public:myvect(int size=2)//初始化{start=new T[size];last=start;end=start+size;}//析构函数~myvect(){delete []start;start=last=end=nullptr;}//拷贝构造函数myvect(const myvect& R){//原空间大小int size=R.last-R.start;int len&#d-R.start;//申请新空间start=new T[len];memcpy(start,R.start,sizeof(T)*size);last=start+size;end=start+len;}//判空bool empty(){return last==start?1:0;}//判满bool full(){return end==last?1:0;}//数据大小int size(){return last-start;}//数组长度int len(){return end-start;}//尾部插入数据void push_tail(const T e){if(full()){greater();}*last=e;last++;}//2倍扩容void greater(){//原来数组的总长度int len=end-start;T *t=new T[len*2];memcpy(t,start,sizeof(T)*len);delete []start;start=t;last=start+len;end=start+len*2;}//尾部删除数据void pop_tail(){if(empty()==true){cout<<"empty"<<endl;return ;}--last;}//at访问成员T& at(int index){if(index<0||index>size()){cout<<"越界访问"<<endl;}return start[index];}//获取第一个元素T front()const{return *start;}};
int main()
{myvect<int> m1;cout<<"size="<<m1.size()<<endl;for(int i=0;i<20;i++){m1.push_tail(i+10);cout<<"size="<<m1.size()<<'t'<<"len="<<m1.len()<<endl;}for(int i=0;i<20;i++){cout<<m1.at(i)<<" ";}cout<<endl;cout << "Hello World!" << endl;return 0;
}