Question

我不知道为什么这个程序不会运行。 getStockInfo中的值应该存储在参考参数中。然后displayStatus接受它们作为参数。我知道它与getStockInfo和displayStatus在main中有关，当它们被定义时，我只是想不通它

#include <iostream>
#include <iomanip>
using namespace std;

void getStockInfo(int &, int&, double&);
void displayStatus(int, int, double, double);

int main()
{
//Declare Variables
int orderedSpools;
int spoolsStock;
double specialCharges;
int spoolsOrdered;

int backOrder;
double subtotal,
       shipping,
       total;


cout << "Middletown Wholesale Copper Wire Company" << endl;

getStockInfo(spoolsOrdered, spoolsStock, specialCharges);

displayStatus(spoolsOrdered, spoolsStock, specialCharges);

  system("pause");
  return 0;
}

void getStockInfo(int &spoolsOrdered, int &spoolsStock, double &specialCharges)
{
char ship; 

cout << "How many spools would you like to order: ";
cin >> spoolsOrdered;

//Validate the spools ordered 
while(spoolsOrdered < 1)
{
    cout << "Spools ordered must be at least one" << endl;
    cin >> spoolsOrdered;
}

cout << "How many spools are in stock: ";
cin >> spoolsStock;

//Validate spools in stock
while(spoolsStock < 0)
{
    cout << "Spools in stock must be at least 0" << endl;
    cin >> spoolsStock;
}

cout << "Are there any special shipping charges? ";
cout << "Enter Y for yes or another letter for no: ";
cin >> ship;

//Validate special charges
if(ship == 'Y' || ship == 'y')
{
    cout << "Enter the special shipping charge: $";
    cin >> specialCharges;
}
else
{
    specialCharges = 10.00;
}
}

void displayStatus(int spoolsOrdered, int spoolsStock, double specialCharges,
                   double total)
{
double backOrder,
       subtotal,
       shipping,
       total;
int itemsReady;


cout << "Items ordered: " << spoolsOrdered << endl;
cout << "Items ready to ship: " << spoolsStock << endl;


if(spoolsOrdered > spoolsStock)
{
    backOrder = spoolsOrdered - spoolsStock;
    cout << "Items on backorder: " << backOrder << endl;
}


subtotal = itemsReady * 100;
cout << "Subtotal: " << subtotal << endl;

shipping = specialCharges;
cout << "Shipping: " << shipping << endl;

total = subtotal + shipping;
cout << "Total Due: " << total << endl;



}

Answer 1

以下是您宣布displayStatus：

的方式

void displayStatus(int, int, double, double);

以下是您使用displayStatus的方式：

displayStatus(spoolsOrdered, spoolsStock, specialCharges);

你看到了区别吗？

提示：计算每行中的参数数量。

Answer 2

void displayStatus(int spoolsOrdered, int spoolsStock, double specialCharges,
                   double total)  //**<-- here: total as parameter**
{
double backOrder,
       subtotal,
       shipping,
       total;  //**<-- and here: total as local variable**
int itemsReady;

在上面的代码中，我发现你有冗余。我标记了它。你有两个同名的变量， total ，一个是displayStatus函数的参数，另一个是displayStatus函数的局部变量。

当我逐行看到你的代码时，这个 total 变量在getStockInfo函数中都没有在main函数中执行任何计算。 total 变量的唯一计算是在displayStatus函数中进行的。因此，我建议你，在displayStatus函数的参数上更好地删除变量 total 。它不会损害您的代码，因为您已经拥有本地变量 total 。

编辑：您在主函数中不需要 total 变量，因此， delete 此变量。

c ++参考参数功能

2 个答案: