C++用户输入Age变量乘算转换月龄天数代码报错求解

你的代码核心问题是变量计算顺序和输入顺序颠倒：

• 你在还没读取用户输入的Age值时，就提前执行了days = 30 * month的计算，此时month和Age都是未初始化的随机值，触发了未定义行为，就是你看到的异常报错。
• 所有依赖Age的计算逻辑，必须放在cin >> Age读取用户输入之后执行。

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

int main()
{
    string visitorname;

    cout << "Hello, welcome to Montgomery College! My name is Nao. May I have your name? \n";
    getline(cin, visitorname);
    cout << "Nice to meet you " << visitorname << "\n";
    cout << "Let me impress you with a small game.\n";
    cout << "Give me the age of an important person or a pet to you.\n Please give me only a number:\n";

    int Age;
    // 先读取用户输入的Age
    cin >> Age;
    // 再用有效Age值计算后续变量
    int month = Age * 12;
    int days = 30 * month;

    cout << "You have entered " << Age << "\n";
    cout << "If this is for a person, the age can be expressed as " << Age << " years ";
    cout << "or " << month << " months ";
    cout << "or " << days << " days (estimated by 30 days per month)\n";

    return 0;
}

• 调整执行顺序：将Age读取逻辑放在所有关联计算之前，保证month、days的计算都是基于用户输入的有效数值
• 去掉了未初始化变量的提前计算步骤，彻底避免未定义行为
• 补充了输出文本的空格和换行，优化显示效果，避免文本内容挤在一起
• 移除了没用的<cmath>头文件引用，减少不必要的编译开销

内容的提问来源于stack exchange，提问作者briana pratt