向量的（查、增、删、改）

  1 #include "stdafx.h"
  2 #include <iostream>
  3 using namespace std;
  4 template <typename T>
  5 #define DEFAULT_CAPACITY 3
  6 class vector
  7 {
  8 private:
  9     int size;
 10     int capacity;
 11     T* elem;                    //定义数据区
 12 public:
 13     vector();                    //构造函数
 14     void insert(T &e, int i);
 15     void expand();                //扩容
 16     void shrink();                //缩容
 17     T remove(int i);            //删除
 18     void print();
 19     T &operator[] (int r);      //重载下标操作符，类似于数组形式引用各元素
 20     int getsize();              //获取当前元素总数
 21 };
 22 
 23 template <typename T>
 24 vector<T>::vector()
 25 {
 26     capacity = DEFAUL_CAPACITY 3
 27         elem = new T[capacity];
 28     size = 0;
 29 }
 30 
 31 template <typename T>
 32 void Vector<T>::insert(T &e, int i)
 33 {
 34     int j;
 35     expand();     //若有必要，扩容
 36     for (j = size; j>i; j++)
 37     {
 38         elem[j] = elem[j - 1];
 39     }
 40     elem[i] = e;
 41     size++;
 42 }
 43 
 44 template <typename T>
 45 void Vector<T>::expand()
 46 {
 47     if (size < capacity)
 48         return;
 49     cout << "expand" << endl;
 50     T *oldElem = elem;
 51     elem = new T[capacity <<= 1];
 52     for (int i = 0; i<size; i++)
 53         elem[i] = oldElem[i];
 54     delete[] oldElem;
 55 }
 56 template <typename T>
 57 T Vector<T>::remove(int i)
 58 {
 59     int j;
 60     T e;
 61     e = elem[i];
 62     for (j = i + 1; j<size; j++)
 63     {
 64         elem[j - 1] = elem[j];
 65     }
 66     size--;
 67     shrink();
 68     return e;
 69 }
 70 template <typename T>
 71 void Vector<T>::shrink()
 72 {
 73     if (capacity < DEFAULT_CAPACITY)
 74         return;
 75     if ((size * 4) <= capacity)
 76     {
 77         cout << "shrink" << endl;
 78         T *oldElem = elem;
 79         elem = new T[capacity >>= 1];
 80         for (int i = 0; i<size; i++)
 81             elem[i] = oldElem[i];
 82         delete[] oldElem;
 83     }
 84 }
 85 
 86 template <typename T>
 87 void Vector<T>::print()
 88 {
 89     int i;
 90     for (i = 0; i<size; i++)
 91         cout << elem[i] << endl;
 92     cout << endl;
 93 }
 94 
 95 template <typename T>
 96 T & Vector<T>::operator[](int r)
 97 {
 98     return elem[r];
 99 }
100 
101 template <typename T>
102 
103 int Vector<T>::getsize()
104 {
105     return size;
106 }