c++ - 我如何在 for 循环内部或外部打印双变量

Question

我正在做一个关于酒店入住率的项目，但我在打印 double 变量时遇到了困难。我需要知道如何使用 setprecision 显示 double 变量。

#include <iostream>

using namespace std;

int main()
{
    int numfloors=0; //for number of floors
    int numrooms=0; //for number of rooms per floor
    int numoccipied=0; //for rooms that are occupied
    int TRooms=0; //for total rooms in hotel
    int TOcuppied=0; //for total rooms occupied in the hotel
    int TUnoccupied=0; //for unoccupied rooms in the hotel
    double occupancy=0; //for persentage occupancy

    cout<<"Enter the number of floors in the hotel"
        <<"\nNote: please do not write value less than 1: ";
    cin>>numfloors;

    for(int floor=1; floor<=numfloors; floor++) //loop starts
    {
        cout<<"how many rooms are there in no."<<floor<<"floor?\n"; //ask user to for number of rooms per floor
        cin>>numrooms;

        TRooms+= numrooms; //total rooms in each floor will add and store in Trooms
        cout<<"how many rooms are ocupied?\n";  //ask user to put number of occupied rooms
        cin>>numoccipied;
        TOcuppied+=numoccipied; //number of rooms occupied per floor is added 
        TUnoccupied=TRooms-TOcuppied; //stores all unoccupied rooms
        occupancy=(TOcuppied)/TRooms; //store persentage occupancy 

        cout<<"\n\nThe Hotel has "<<TRooms<<"rooms\n";
        cout<<"from which "<<TOcuppied<< " rooms are occupied,\n";
        cout<<"and "<<TUnoccupied<<" are Unoccupied.\n ";
    }
    cout << fixed << showpoint << setprecision(1);
    cout<<"\n\nOccupancy Rate: "<<occupancy*100<<"% \n\n";
    return 0;
}

Answer 1

您似乎是初学者，所以我将列出您的代码的一些问题:

1. 当两个整数相除时，结果也是一个整数。因此，在整数除法中，4/10 为 0。因此，此行始终生成零:

   occupancy=(TOcuppied)/TRooms;
   

   改为使用:

   occupancy=(TOcuppied)/(double)TRooms;
   

2. cout 的设置显然必须全部在输入之前进行。所以首先发送设置:

   cout << fixed << showpoint << setprecision(1);
   

   然后:

   cout << occupancy*100;
   

   当然也可以放在一行中:

   cout << fixed << showpoint << setprecision(1)<< occupancy*100;
   

3. 您允许某些类型的无效输出。由于您的作业看起来很像家庭作业，因此您可能需要对它们进行清理。一种是您允许一个人进入比可用房间更多的房间:

   how many rooms are there in no.1floor?
   10
   how many rooms are ocupied?
   20
   
   The Hotel has 10rooms
   from which 20 rooms are occupied,
   and -10 are Unoccupied.
   
   Occupancy Rate: 200.00%
   

   所以记得检查输入:

   if(numoccipied>numrooms) {
       // do something, such as asking the user to enter correct value
   }
   

   同样，你应该阻止用户进入不到一层楼:

   if(numfloors<1)
       return 0;