Question

我的程序中出现此错误

1>c:\users\kanaan\documents\visual studio 2010\projects\assign2\assign2\vending machine.h(36): error C2057: expected constant expression
1>c:\users\kanaan\documents\visual studio 2010\projects\assign2\assign2\vending machine.h(36): warning C4200: nonstandard extension used : zero-sized array in struct/union
1>          Cannot generate copy-ctor or copy-assignment operator when UDT contains a zero-sized array
1>  MakeSelection.cpp
1>c:\users\kanaan\documents\visual studio 2010\projects\assign2\assign2\vending machine.h(36): error C2057: expected constant expression
1>c:\users\kanaan\documents\visual studio 2010\projects\assign2\assign2\vending machine.h(36): warning C4200: nonstandard extension used : zero-sized array in struct/union
1>          Cannot generate copy-ctor or copy-assignment operator when UDT contains a zero-sized array
1>c:\users\kanaan\documents\visual studio 2010\projects\assign2\assign2\makeselection.cpp(13): error C2082: redefinition of formal parameter 'ItemPrice'
1>c:\users\kanaan\documents\visual studio 2010\projects\assign2\assign2\makeselection.cpp(14): error C2082: redefinition of formal parameter 'NumItems'
1>  Main.cpp
1>c:\users\kanaan\documents\visual studio 2010\projects\assign2\assign2\vending machine.h(36): error C2057: expected constant expression
1>c:\users\kanaan\documents\visual studio 2010\projects\assign2\assign2\vending machine.h(36): warning C4200: nonstandard extension used : zero-sized array in struct/union
1>          Cannot generate copy-ctor or copy-assignment operator when UDT contains a zero-sized array
1>  DisplayErrorMessage.cpp
1>c:\users\kanaan\documents\visual studio 2010\projects\assign2\assign2\vending machine.h(36): error C2057: expected constant expression
1>c:\users\kanaan\documents\visual studio 2010\projects\assign2\assign2\vending machine.h(36): warning C4200: nonstandard extension used : zero-sized array in struct/union
1>          Cannot generate copy-ctor or copy-assignment operator when UDT contains a zero-sized array

需要帮助。

这是一个完整的编码。

头文件：

#ifndef _VENDING_MACHINE_H_
#define _VENDING_MACHINE_H_

#include <iostream>
#include <cmath>
#include <string>

using namespace std;

  extern int Denominations;
  extern int const ITEMS;

  extern int Coins[];
  extern int NumCoins[]; //assume we have 10 coins of each denomination

  extern int ItemPrice[ ]; //price in cents
  extern int NumItems[ ]; 

  extern double Total_Price;
  extern double Item_Total;

class VendingMachine{
public:
    void MakeSelection(int NumItems [], int ItemPrice[]);
    int ReturnChange(int change, int Coins[], int NumCoins[]);
    void ShowMenu();
    void DisplayErrorMessage(int error);
    void PrintConfidentialInformation(int Denominations, int Items, int Coins[], 
                                                int NumCoins[], int ItemPrice[] , int NumItems[]);

private:
    int selection;
    string code;
    double Each_Item[ITEMS];       //price for each item
};
#endif //_VENDING_MACHINE_H_

cpp文件：

#include "Vending Machine.h"

void VendingMachine::MakeSelection(int NumItems [], int ItemPrice[]){

   int Denominations = 5;
   int const ITEMS = 9;

   int Coins[] = {100, 50, 20, 10, 5};
   int NumCoins[] = {10, 10, 10, 10, 10}; //assume we have 10 coins of each denomination



  int ItemPrice[ ] = { 75, 120, 120, 100, 150, 95, 110, 50, 120 }; //price in cents
  int NumItems[ ] = { 10, 10, 10, 10, 10, 10, 10, 10, 10 }; 

string Product[ITEMS] = {"Water","Coke","Diet Coke","Iced Tea","Swiss Chocolate","Candy",
                                                    "Chips","Bubble Gum","Turkish Delight"};
   int b = 0;
int a = 1;

cout << "Please enter the number of your choice from the menu above. " << endl;

do{
    cout << "\nEnter the number of product OR End transaction: " << endl;
    cin >> selection;
    cout << "\nYou have selected " <<Product[selection] << endl;

    if(selection >= 1 && selection <= 9){

        NumItems[selection - 1] = NumItems[selection - 1] - 1;

        if(NumItems[selection - 1] >= 0)
            Total_Price = Total_Price + ItemPrice[selection - 1];

        else{
            int error = 1;
            DisplayErrorMessage(error);         //Item finised
            cout <<selection<< endl;
        }
    }
    else if(selection == 10)
        cout << "\nTransaction Ended" << endl;

    else if(selection == 99){

        cout << "Enter the code to access maintanance: " <<endl;
        cin >> code;

        while(code != "111"){
            int error = 2;
            DisplayErrorMessage(error);
            cin >> code;
        }

        cout << endl;
        cout << "\t\t\t\t\tSales Report " << endl;
        cout << "==================================================== " << endl;
        cout << endl;
        cout << "Number of each product sold with Income cost: " << endl;
        cout << endl;

        do{
            if(NumItems[b] >= 0){

                Each_Item[b] = Each_Item[b] + ItemPrice[b];

                cout << NumItems[b] << "" << Product[b] << " sold for the total cost of " <<(10 - NumItems [b]) * Each_Item[b]/ 100 <<endl;   

                Total_Price = Total_Price + ((10 - NumItems[b]) * Each_Item[b]/100);
            }
            b++;
        }while(a <= ITEMS);
    }
    else{ 
        int error = 3;
        DisplayErrorMessage(error);
    }
}while(selection != 10);
}

在这里需要一些帮助我无法识别错误。我试图在头文件中声明全局变量，所以我可以在任何cpp文件中使用它，但我在顶部显示错误。

这样做是对还是错？

  #include "Vending Machine.h"

  int main(){

   int Num_Items[ITEMS], Item_Price[ITEMS];
   VendingMachine ex;
   ex.ShowMenu();
   ex.MakeSelection(Num_Items, Item_Price);

   system("PAUSE");
   return 0;
  }

Answer 1

ITEMS需要在同一翻译单元中提供的定义才能用作数组大小。将其声明（extern int const ITEMS;）更改为定义：

int const ITEMS = 9;

当UDT包含零大小的数组时，无法生成copy-ctor或copy-assignment运算符

1 个答案: