Question

我是C ++的新手，并且陷入了互换的境地下面的代码是按照字母顺序排序员工姓名的程序，并打印出原始的和排序的一个，但是交换方法不起作用 printEmployees的两个输出非常相似，任何人都可以帮助我吗？ THX

    #include <iostream>

    #include <string>

    #include <iomanip>

    #include <algorithm>
using namespace std;


class employee
{

   /* Employee class to contain employee data
   */

   private:
     string surname;
     double hourlyRate;
     int empNumber; 
   public:
      employee() {
         hourlyRate = -1;
         empNumber = -1;
         surname = "";
      }
      employee(const employee &other) :
         surname(other.surname),
         hourlyRate(other.hourlyRate),
         empNumber(other.empNumber){}

      void setEmployee(const string &name, double rate,int num);
      string getSurname() const;
      void printEmployee() const;
     employee& operator = (const employee &other)
    {employee temp(other);
     return *this;}};    

     void employee::setEmployee(const string &name, double rate, int num) {   
      surname = name;
      hourlyRate = rate;
      empNumber = num;
      }
     string employee::getSurname() const { return surname; }  
     void employee::printEmployee() const {
         cout << fixed;
         cout << setw(20) << surname << setw(4) << empNumber << "  " << hourlyRate << "\n";
      }

  void printEmployees(employee employees[], int number)
   {
   int i;
    for (i=0; i<number; i++) { employees[i].printEmployee();   }
   cout << "\n";
   }


void swap(employee employees[], int a, int b)
{
  employee temp(employees[a]);
employees[a] = employees[b];
employees[b] = temp;

}


void sortEmployees(employee employees[], int number)
{
   /* use selection sort to order employees, 
      in employee 

name order
   */


    int inner, outer, max;


    for (outer=number-1; outer>0; outer--)
   {
      // run though array number of times
      max = 0;
      for (inner=1; 

inner<=outer; inner++)
      {
         // find alphabeticaly largest surname in section of array
         if (employees

[inner].getSurname() < employees[max].getSurname())
            max = inner;
      }
      if (max != outer)
      {
         // 

swap largest with last element looked at in array
         swap(employees, max, outer);
      }
   }
}


int main()
{
   employee employees[5];

   employees[0].setEmployee("Stone", 35.75, 053);
   employees[1].setEmployee

("Rubble", 12, 163);
   employees[2].setEmployee("Flintstone", 15.75, 97);
   employees[3].setEmployee("Pebble", 10.25, 104);


  employees[4].setEmployee("Rockwall", 22.75, 15);


   printEmployees(employees, 5);

   sortEmployees(employees,5);
   printEmployees(employees, 5);

   return 0;
}

Answer 1

此代码已损坏：

 employee& operator = (const employee &other)
{employee temp(other);
 return *this;}

应该是这样的：

employee& operator= (const employee &other)
{
   surname = other.surname;
   hourlyRate = other.hourlyRate;
   empNumber = other.empNumber;
   return *this;
}

Answer 2

正如其他人所说，修理任务操作员将解决问题我看到你试图在复制构造函数方面实现operator=但是错过了交换。如果要避免复制构造函数和赋值运算符中的代码重复，可以尝试以下方法。

employee& operator=(const employee& other)
{
    employee temp(other);
    swap(temp);
    return *this;
}

void swap(employee& other)
{
     std::swap(surname, other.surname);
     std::swap(hourlyRate, other.hourlyRate);
     std::swap(empNumber, other.empNumber);
}

无法在C ++中交换数组中的对象

2 个答案: