请解决/回答 C++函数变量的程序问题

Question

请解决/回答问题以使程序正常运行。我没有完全理解通过引用或值传递变量，我认为这就是让这变得如此困难的原因。所以如果你能修复这个程序。过去两天我一直在做这个。我已经包含了完整的代码。

paxdiablo 建议这样做，我正在尝试按照他们所说的去做

“您应该做的一件事是在主函数中将 TotalSqrtfeet 初始化为零。那是因为您只是将每个房间的大小添加到其中，并且它以随机值：垃圾+ a + b + c + d仍然是垃圾:-)

最重要的是，您从主函数中调用getUserData，然后再次从doEstimate中调用它们，这就是它询问的原因。只需调用一次 getUserData 即可，因为这是作业，我会让您弄清楚在哪里，但这里有一个提示，如果您在 main 中执行此操作（轻移、轻移、眨眼、眨眼），则必须传递变量。也进入 doEstimate 中，不要在该函数中创建同名的新变量，并神奇地期望编译器将它们与原始变量关联起来。 “

当我输入 1 个房间、110 平方英尺、15.00 的测试数据时。我在报告功能中得到了正确的房间编号，但其他所有房间的编号均为 0

 #include <iostream>
#include <cstdlib>
#include <cmath>
#include <iomanip>

using namespace std;

// Function prototypes
void showMenu();
void getUserData(int &, int &, double &);
void doEstimate(int &, int &, double &, int &, double &, int &, double &, double &);
void showReport(int &, int &, double &, int &, double &, int &, double &, double &);

int main()
{
    int choice = 0;
    int calcGallonsOfPaint = 0, rooms = 0, totalsqrtfeet = 0;
    double calcCostOfPaint = 0, costOfPaint = 0;
    int calcHoursOfLabor = 0;
    double calcLaborCost = 0;
    double calcPaintJobCost = 0;

   // Set up numeric output formatting.
   cout << fixed << showpoint << setprecision(2);

   do
   {
      // Display the menu and get the user's choice.
      showMenu();
      cin >> choice;

      // Validate the menu selection.
      while (choice < 1 || choice > 2)
      {
         cout << "Please enter 1 or 2: ";
         cin >> choice;
      }

      if (choice == 1)
      {

        //User enters information
        getUserData(rooms, totalsqrtfeet, costOfPaint);

        //Information from getUserData is used to make calculations
        doEstimate(rooms, totalsqrtfeet, costOfPaint, calcGallonsOfPaint, calcCostOfPaint, calcHoursOfLabor, calcLaborCost, calcPaintJobCost);

        //Report is generated from user input and calculations
        showReport(rooms, totalsqrtfeet, costOfPaint, calcGallonsOfPaint, calcCostOfPaint, calcHoursOfLabor, calcLaborCost, calcPaintJobCost);

       }
   } while (choice != 2);
   return 0;
}

//*****************************************************************
// Definition of function showMenu which displays the menu.       *
//*****************************************************************

void showMenu()
{
   cout << "\n\t\tPaint Job Estimator Menu\n\n";
   cout << "1. Get Paint Job Estimate\n";
   cout << "2. Quit the Program\n\n";
   cout << "Enter your choice: ";
}

/*
After the paint job estimate is displayed, the menu should be displayed again. 
The number of rooms must be at least 1, the price of the paint per gallon must be at least $15.00, 
and the area for the wall space of each room must be greater than 10 square feet. 
All input validation must be performed with a loop.
*/

void getUserData(int &rooms, int &totalsqrtfeet, double &costOfPaint)
{
    int sqrtfeet;
    int count = 0;

    cout << "Please enter the number of rooms to be painted: ";
    cin >> rooms;

    cout << "Please enter square feet of wall space in room 1: ";
    cin >> sqrtfeet;

    for (count = 2; count <= rooms; count++)
        {   
            cout << "Please eneter square feet of wall space in room " << count << ": ";
            cin >> sqrtfeet;
            totalsqrtfeet += sqrtfeet;
        }   

    cout << "What is the cost of the paint: ";
    cin >> costOfPaint;
}

void doEstimate(int &rooms, int &totalsqrtfeet, double &costOfPaint, int &calcGallonsOfPaint, double &calcCostOfPaint, int &calcHoursOfLabor, double &calcLaborCost, double &calcPaintJobCost)
{


    calcGallonsOfPaint = 1 * (totalsqrtfeet/110);           //Calculates the number of whole gallons of paint required.

    calcCostOfPaint = calcGallonsOfPaint  * costOfPaint;    //Calculates the cost of the paint required.

    calcHoursOfLabor = calcGallonsOfPaint * 6;              //Calculates the number of whole hours of labor required.

    calcLaborCost = calcHoursOfLabor * 15.00;               //Calculates the labor charges.

    //Calculates the cost of the paint job. This is the sum of the labor charges and the cost of the paint required.
    calcPaintJobCost = calcLaborCost + calcCostOfPaint;     


}

void showReport(int &rooms, int &totalsqrtfeet, double &costOfPaint, int &calcGallonsOfPaint, double &calcCostOfPaint, int &calcHoursOfLabor, double &calcLaborCost, double &calcPaintJobCost)
{


    cout << "The number of rooms to be painted: " << rooms << endl;
    cout << "The number of whole gallons of paint required: " << calcGallonsOfPaint << endl;
    cout << "The hours of labor required: " << calcHoursOfLabor << endl;
    cout << "The cost of the paint: " << calcCostOfPaint << endl;
    cout << "The labor charges: " << calcLaborCost << endl;
    cout << "The total cost of the paint job: " << calcPaintJobCost << endl;

    system("pause");
    system("cls");
}

Answer 1

这是错误的

if (choice == 1)
{
    getUserData();
    doEstimate();
    showReport();
}

你的原型是

void getUserData(int &rooms, double &costOfPaint, int &totalsqrtfeet);
void doEstimate(int &calcGallonsOfPaint, double &calcCostOfPaint, int &calcHoursOfLabor, double &calcLaborCost, double &calcPaintJobCost);
void showReport();

你需要的

int rooms;
double costOfPaint;
int totalsqrtfeet;

getUserData(rooms, costOfPaint, totalsqrtfeet);

Answer 2

你的问题在这里：

getUserData();
doEstimate();
showReport();

这些函数都带有参数。你没有给他们任何东西。解决方案是为他们提供所需的论据。

他们似乎正在采用用作输出参数的参考参数。你可以这样称呼它们：

void foo(int& out_param) 
{
   out_param = 1;
}

int main() 
{
   int x = 0;      // Create a variable of the appropriate type to pass 
   foo(x);         // Give it as a parameter to foo
   std::cout << x; // x is now 1, so this should print 1

   return 0;
}

我不会为你的特定问题提供直接的解决方案，因为这显然是家庭作业，但这应该会让你走上正确的轨道。

Answer 3

不确定这是否与您的问题有关（您并没有真正解释那是什么），但在函数 doEstimate 中您有：

getUserData (double &costOfPaint, int &totalsqrtfeet);

我不确定您在这里想做什么，但作为它是一个函数原型声明，没有任何用处。或许你另有目的？如果你想调用这个函数，你应该这样做，其中 var1、var2 和 var3 是一些必须在之前声明的变量这个调用：

getUserData(var1, var2, var3);

稍后你会发现：

calcGallonsOfPaint: 1 * (totalsqrtfeet/110);

这应该是 = 而不是 :。

Answer 4

我建议使用（源代码级）调试器逐步调试您的程序，以查看每行代码发生了什么。它是一个不可或缺的工具，可以非常轻松地跟踪程序中的意外行为，并为您节省大量时间。

只需在 google 上搜索适合您正在使用的编程环境/IDE 的调试器教程即可。但一般来说，在使用任何调试器时，您都希望在代码中设置断点，然后单步执行每一行并查看程序的当前状态，检查变量等。

Answer 5

一个班最多有 30 名学生。每个学生都通过姓氏、姓名和平均成绩来识别。它要求学生展示：

1. 按环境降序排列；
2. 按字母顺序排列。