码图：165 （多态）Set类（C++）

题目描述：

引入头文件CSet.h,它的内容如下：

#include <iostream> using namespace std; class Set{ private: int n; int * pS; //集合元素 public: Set(){n = 0;pS =NULL;} Set(Set &s){ n = s.n; if (n !=0) { pS= new int[n+1]; for (int i =1;i<=n;i++) //集合的下标从1开始，集合中不能有重复元素 pS[i] = s.pS[i]; } } ~Set(){ if (pS) { delete []pS; pS = NULL; n =0; } } void ShowElement()const{ //输出集合的元素 int temp = 0; for(int i=1;i<n;i++) { for(int j=i+1;j<n;j++) { if(pS[i] > pS[j]) { temp = pS[i]; pS[i] = pS[j]; pS[j] = temp; } } } cout<<"{"; for(int i =1;i<n;i++) cout <<pS[i]<<","; if (IsEmpty()) cout<<"}"<<endl; else cout<<pS[n]<<"}"<<endl; } bool IsEmpty()const{return n?false:true;} //判断集合是否为空 int size(){return n;} bool IsElement(int e)const { for (int i =1;i<=n;i++) if (pS[i] ==e) return true; return false; } bool operator <=(const Set &s)const;//this <= s判断当前集合是否包于集合s bool operator ==(const Set &s)const; //判断集合是否相等 Set & operator +=(int e); // 向集合中增减元素e Set & operator -=(int e); //删除集合中的元素e Set operator |(const Set &s)const; //集合并 Set operator &(const Set &s)const;//集合交 Set operator -(const Set &s)const; //集合差 };

完成Set类，实现运算符的重载。 重载操作符+=,向集合中增减元素e,例如:

Set s; s +=1; s.ShowElement();//{1}

重载操作符-=,删除集合中元素e,例如:

Set s; s +=1,s+=2; s.ShowElement();//{1,2} s -=1; s.showElement();//{2}

重载操作符<=,判断当前集合是否包于另一个集合，例如:

Set s1,s2,s3; s1 +=1; s2+=1;s2+=3; s3+=2; s1 <=s2;//true s3 <=s2//false;

重载操作符==,判断集合是否相等,例如:

Set s1 s2; s1 == s2;//true s1+=1;s2+=2; s1 ==s2 ;//false;

重载操作符|,集合并,例如:

Set s1 s2; s1+=1;s2+=2; s1|s2 ;//{1,2}

重载操作符&,集合交,例如:

Set s1 s2; s1+=1;s2+=2;s2+=1; s1&s2 ;//{1}

重载操作符-,集合差,例如:

Set s1 s2; s1+=1;s1+=3;s2+=2;s2+=1; s1-s2 ;//{3}

解答：

#include<iostream> #include"CSet.h" bool Set::operator <=(const Set& s)const { bool is_in = false; int i = 1, j; for (i = 1; i <= n; i++) { is_in = false; for (j = 1; j <= s.n; j++) if (s.pS[j] == pS[i]) { is_in = true; break; } if (!is_in) return false; } return true; } bool Set::operator ==(const Set& s)const { bool outcome = false; if (s.n != n) return outcome; outcome = ((*this) <= s); return outcome; } Set& Set::operator +=(int e) { int i; bool is_in = false; for (i = 1; i <= n; i++) { if (e == pS[i]) { is_in = true; break; } } if (!is_in) { int* temp = pS; n++; pS = new int[n + 1]; for (i = 1; i < n; i++) pS[i] = temp[i]; pS[n] = e; } return *this; } Set& Set::operator -=(int e) { int i, pos = 0; for (i = 1; i <= n; i++) { if (pS[i] == e) { pos = i; break; } } if (pos == 0) return *this; for (i = pos; i < n; i++) pS[i] = pS[i + 1]; n--; return *this; } Set Set::operator |(const Set& s)const { int cnt = 0; int* temp = new int[this->n + s.n + 1]; for (int i = 1; i <= n; i++) temp[++cnt] = pS[i]; int i, j; bool is_in = false; for (i = 1; i <= s.n; i++) { is_in = false; for (j = 1; j <= n; j++) if (s.pS[i] == pS[j]) { is_in = true; break; } if (!is_in) temp[++cnt] = s.pS[i]; } Set uni; uni.n = cnt; uni.pS = temp; return uni; } Set Set::operator &(const Set& s)const { int* temp = new int[min(n, s.n) + 1]; int cnt = 0; int i, j; bool is_in = false; for (i = 1; i <= s.n; i++) { is_in = false; for (j = 1; j <= n; j++) if (s.pS[i] == pS[j]) { is_in = true; break; } if (is_in) temp[++cnt] = s.pS[i]; } Set con; con.n = cnt; con.pS = temp; return con; } Set Set::operator -(const Set& s)const { int* temp = new int[n + 1]; int i, j, cnt = 0; bool is_in = false; for (i = 1; i <= n; i++) { is_in = false; for (j = 1; j <= s.n; j++) if (s.pS[j] == pS[i]) { is_in = true; break; } if (!is_in) temp[++cnt] = pS[i]; } Set dif; dif.n = cnt; dif.pS = temp; return dif; }