类与对象 重载 实验十三 期末回顾

实验题目录：​​点击打开链接​​

1.第一题

1、阅读程序，其中s::connect函数实现字符串连接。把这个成员函数改写为重载+运算符函数，并修改main函数的对应代码，使其正确运行。

#include <iostream>
#include<cstring>
using namespace std;
class s
{  public:
      s() { *str = '\0'; len = 0; }
      s( char *pstr )
      {  strcpy_s( str,pstr );  len = strlen(pstr);  }
      char *gets() {  return str;  }
      int getLen() {  return len;  }
      s connect( s obj );        //字符串连接函数声明
   private:
      char str[100];
      int len;
};
s s::connect( s obj )            //字符串连接函数定义
{  strcat_s( str,obj.str );
      return str; 
}
int main()
{  s obj1( "Visual" ), obj2( " C++" ), obj3(" language");
   obj3 = (obj1.connect(obj2)).connect(obj3);      //调用字符串连接函数
   cout << "obj3.str = "<<obj3.gets() << endl;
   cout<<"obj3.len = "<<obj3.getLen()<<endl;
   return 0;
}

友元函数重载：

#include <iostream>
#include<cstring>
using namespace std;
class s
{  public:
      s() { *str = '\0'; len = 0; }
      s( char *pstr )
      { strcpy( str,pstr );  len = strlen(pstr);  }
      char *gets() {  return str;  }
      int getLen() {  return len;  }
      friend s &operator +(s&a,s&b)   //注意operator前有&
      {
         strcat(a.str,b.str);
      a.len = strlen(a.str);
         return a;
      }
   private:
      char str[100];
      int len;
};
int main()
{  s obj1( "Visual" ), obj2( " C++" ), obj3(" language");
   obj3 =obj1+obj2+obj3;      //调用字符串连接函数
   cout << "obj3.str = "<<obj3.gets() << endl;
   cout<<"obj3.len = "<<obj3.getLen()<<endl;
   return 0;
}

成员函数重载：

#include <iostream>
#include<cstring>
using namespace std;
class s
{  public:
    s() 
    { *str = '\0'; len = 0; }
    s( char *pstr )
    {  strcpy( str,pstr );
      len = strlen(pstr);
      
    }
    char *gets()
    {  return str; }
    int getLen()
    {  return len; }
    s operator+( s obj );
  private:
     char str[100];
     int len;
};
s s::operator+(s obj )
{
   strcat( str,obj.str );
   return str; 
} 
int main()
{
  s obj1( "Visual" ), obj2( " C++" ), obj3(" language");
  obj3 = obj1 + obj2 + obj3;
  cout << "obj3.str = "<<obj3.gets() << endl;
  cout<<"obj3.len = "<<obj3.getLen()<<endl;
        return 0;
}

2.第二题

2、改写下述程序中的student类，用重载运算符>>函数代替input函数；用重载运算符<<函数代替output函数；并修改main函数，使其得到正确的运行结果。

#include <iostream>
using namespace std;
class student
{    char name[20];
      unsigned id;
      double score;
   public:
      student(char s[20]="\0", unsigned k=0, double t=0)
      {  strcpy_s(name,s);
         id=k;
         score=t;
      }
      void input()
      {  cout<<"name? ";
         cin>>name;
         cout<<"id? ";
         cin>>id;
         cout<<"score? ";
         cin>>score;      }
      

      void output()
      {  cout<<"name: "<<name<<"\tid: "<<id<<"\tscore: "<<score<<endl;  }
};
int main()
{  student s;
   s.input();
   s.output();
   return 0;
}

实现代码：

#include <iostream>
#include<cstring>
using namespace std;
class student
{    char name[20];
      unsigned id;
      double score;
   public:
      student(char s[20]="\0", unsigned k=0, double t=0)
      {  strcpy(name,s);
         id=k;
         score=t;
      }
      friend istream& operator>>(istream&input,student&s)
      {
        cout<<"name? ";
         input>>s.name;
         cout<<"id? ";
         input>>s.id;
         cout<<"score? ";
         input>>s.score;
         return input;
      }

      friend ostream& operator<<(ostream&output,student&s)
      {
          output<<"name: "<<s.name<<"\tid: "<<s.id<<"\tscore: "<<s.score<<endl;
          return output;
      }

};
int main()
{  student s;
  cin>>s;
  cout<<s;
   return 0;
}