如何基于重量和距离在C++程序中计算包裹运输费用

计算逻辑拆解 #

• 第一步：根据包裹重量匹配单位费率
  • ≤2kg：对应twoOrLess常量1.10美元/500英里
  • 2kg<重量≤6kg：对应twoToSix常量2.20美元/500英里
  • 6kg<重量≤10kg：对应sixToTen常量3.70美元/500英里
  • 10kg<重量≤20kg：对应tenToTwenty常量4.80美元/500英里
• 第二步：计算计费距离段数
  规则为不足500英里按500英里计算，可通过整数运算向上取整实现：(int)(distance + 499) / 500，不需要额外调用数学库函数
• 第三步：总运费 = 单位费率 × 计费段数

完整修正代码 #

首先需要引入<iomanip>头文件用于格式化金额输出，同时修正原代码中重量校验条件错误、距离超3000无提示、拼写错误等问题：

#include <iostream>
#include <iomanip>
using std::cout;
using std::cin;
using std::endl;
using std::fixed;
using std::setprecision;

double weight, distance;
const double twoOrLess = 1.10;
const double twoToSix = 2.20;
const double sixToTen = 3.70;
const double tenToTwenty = 4.80;

int main()
{
    cout << "Welcome to Shippers R Us!" << endl 
         << "------------------------"  << endl;
    // 全局设置金额输出保留2位小数
    cout << fixed << setprecision(2);
    
    do
    {
        cout << "Package weight(in Kg, 0 to end): ";
        cin >> weight;
        
        while (weight < 0 || weight > 20)
        {
            if (weight == 0)
            {
                break;
            }
            else if (weight < 0)
            {
                cout << "weight must be greater than zero." << endl;
                cout << "------------------------" << endl;
                cout << "Package weight(in Kg, 0 to end): ";
                cin  >> weight;
            }
            else if (weight > 20)
            {
                cout << "We do not ship items weighing more than 20 kilograms." << endl;
                cout << "------------------------" << endl;
                cout << "Package weight(in Kg, 0 to end): ";
                cin >> weight;
            }
        }

        if (weight == 0)
        {
            break;
        }

        cout << "Distance(in miles): ";
        cin >> distance;

        while (distance < 10 || distance > 3000)
        {
            cout << "Distance must be between 10 and 3,000 miles." << endl << "Distance(in miles): ";
            cin >> distance;
        }
        
        // 运费计算逻辑
        double rate;
        if (weight <= 2) {
            rate = twoOrLess;
        } else if (weight <= 6) {
            rate = twoToSix;
        } else if (weight <= 10) {
            rate = sixToTen;
        } else {
            rate = tenToTwenty;
        }
        int segments = (int)(distance + 499) / 500;
        double shippingCost = rate * segments;
        
        // 输出结果
        cout << "Shipping cost: $" << shippingCost << endl;
        cout << "------------------------" << endl;

    } while (weight != 0);
    return 0;
}

关键逻辑说明 #

• 重量匹配用多分支if-else判断，因为区间是连续的，前面的条件已经排除了更小的重量，所以后续判断不需要再写下限
• 向上取整计算段数的逻辑：给距离加499后截断整数部分再除以500，刚好实现不足500进1的需求，例如499英里得到1段，500英里得到1段，501英里得到2段，完全符合计费规则
• 用fixed和setprecision(2)确保输出金额始终保留两位小数，符合货币显示习惯

内容的提问来源于stack exchange，提问作者SamXeox