【自考】C++程序设计—operator案例

//201910真题

#include <iostream>
#include <string>
using namespace std;
class str
{
private:
     char *st;
public:
     str(char *a){
        set(a);
     }
     str& operator=(str &a)
     {
         delete st;
           set(a.st);
           return *this;
     }
     void show(){
         cout<<st<<endl;
     }
     ~str(){delete st;}
     void set(char *s)
     {
        st=new char[strlen(s)+1];
        strcpy(st,s);
     }
};
void main(){
  str s1("he"),s2("she");
  s1.show(),s2.show();
  s2=s1;
  s1.show(),s2.show();
}

重载提取运算符 >> 和插入运算符 <<。

#include <iostream>
using namespace std;
class Distance
{
   private:
      int feet;             // 0 到无穷
      int inches;           // 0 到12
   public:
      // 所需的构造函数
      Distance(){
         feet = 0;
         inches = 0;
      }
      Distance(int f, int i){
         feet = f;
         inches = i;
      }
      friend ostream &operator<<( ostream &output, const Distance  &D )
      {
         output << "F : " << D.feet << " I : " << D.inches;
         return output;            
      }
      friend istream &operator>>( istream  &input, Distance &D )
      {
         input >> D.feet >> D.inches;
         return input;            
      }
};
int main()
{
   Distance D1(11, 10), D2(5, 11), D3;
   cout << "Enter the value of object : " << endl;
   cin >> D3;
   cout << "First Distance : " << D1 << endl;
   cout << "Second Distance :" << D2 << endl;
   cout << "Third Distance :" << D3 << endl;
   return 0;
}

 

#include <iostream>
using namespace std;
class Distance
{
private:
     int feet;             // 0 到无穷
     int inches;           // 0 到12
public:
     // 所需的构造函数
     Distance(){
           feet = 0;
           inches = 0;
     }
     Distance(int f, int i){
           feet = f;
           inches = i;
     }
      ostream& operator<<( ostream & os)
     {
           os<<"英寸："<<feet<<"\n英尺："<<inches;
           return os;
     }
};
int main ()
{
     Distance d1(20,18);
     d1<<cout;//相当于d1.operator<<(cout)
}

赋值运算符重载

#include <iostream>
using namespace std;
class Distance
{
   private:
      int feet;             // 0 到无穷
      int inches;           // 0 到12
   public:
      // 所需的构造函数
      Distance(){
         feet = 0;
         inches = 0;
      }
      Distance(int f, int i){
         feet = f;
         inches = i;
      }
      void operator=(const Distance &D )
      {
         feet = D.feet;
         inches = D.inches;
      }
      // 显示距离的方法
      void displayDistance()
      {
         cout << "F: " << feet <<  " I:" <<  inches << endl;
      }
      
};
int main()
{
   Distance D1(11, 10), D2(5, 11);
   cout << "First Distance : ";
   D1.displayDistance();
   cout << "Second Distance :";
   D2.displayDistance();
   // 使用赋值运算符
   D1 = D2;
   cout << "First Distance :";
   D1.displayDistance();
   return 0;
}