c++ - 无法正确嵌套我的错误消息

Question

当用户输入的值等于或小于零以正确嵌套时，我无法获取错误消息。我不确定它应该去哪里，或者我是否需要完全做其他事情。任何帮助，将不胜感激。以下是我的代码。

说明: “某软件公司销售零售价为 99 美元的软件包。数量折扣按以下顺序给出:”10-19 = 20% 折扣，20-49 = 30% 折扣，50-99 = 40% 折扣，100+ = 50 ％ 折扣。 编写一个程序，询问购买的单位数量并计算购买的总成本。 输入验证:决定程序应如何处理小于 0 的输入。

#include <iostream>
#include <iomanip> // needed for setprecision
#include <stdio.h>

using namespace std; // need to use cout, cin, etc.

int main()
{
    double quantity, package = 99.00, initialPrice, discPrice, discount, calcDiscount, percent; // using double here because future multiplication by .2

    cout << "This program will calculate how much of a discount you may receive,\nbased on how many software packages you buy.\n\n";
    cout << "How many software packages do you intend to purchase?\n\n";
    cin >> quantity;

    {
        if (quantity <= 0)
            cout << "\nThat is not an acceptable amount. Please re-run the program with a amount greater than zero.\n\n";
    }

    if ( quantity >= 10 && quantity <= 19)
        discount = 0.2, percent = 20;
    else if ( quantity >= 20 && quantity <= 49)
        discount = 0.3, percent = 30;
    else if ( quantity >= 50 && quantity <= 99)
        discount = 0.4, percent = 40;
    else if ( quantity >= 100 )
        discount = 0.5, percent = 50;
    else if (quantity <10 && quantity >=1)
        discount = 0, percent = 0;

    {
        initialPrice = package * quantity;
        calcDiscount = (discount * package * quantity);
        discPrice = initialPrice - calcDiscount;
        cout << "\nThe total price for " << quantity << " software packages, minus a " << percent << "% discount of $";
        cout << fixed << showpoint << setprecision(2) << calcDiscount << ",";
        cout << " is $" << fixed << showpoint << setprecision(2) << discPrice << ".\n\n";
    }

    return 0;
}

Answer 1

您的代码可以这样修复:

if (quantity <= 0)
{
     cout << "\nThat is not an acceptable amount. Please re-run the program with a amount greater than zero.\n\n";
     return -1;
}
else if ( quantity < 10)
    discount = 0, percent = 0;
else if ( quantity < 20)
    discount = 0.2, percent = 20;
else if ( quantity < 50)
    discount = 0.3, percent = 30;
else if ( quantity < 100)
    discount = 0.4, percent = 40;
else discount = 0.5, percent = 50;

initialPrice = package * quantity;
calcDiscount = (discount * package * quantity);
discPrice = initialPrice - calcDiscount;
cout << "\nThe total price for " << quantity << " software packages, minus a " << percent << "% discount of $";
cout << fixed << showpoint << setprecision(2) << calcDiscount << ",";
cout << " is $" << fixed << showpoint << setprecision(2) << discPrice << ".\n\n";

应该做一些其他的小改动以使代码看起来更好 - 这取决于您