C++心率计算程序可执行但输出异常，寻求技术排查建议

看起来你遇到的核心问题是数据没有正确存入类的成员变量，再加上年龄计算逻辑有误，导致输出不符合预期。咱们一步步拆解问题，然后给出修正后的代码：

1. 最关键的问题：Setter方法和构造函数没有正确给类成员赋值 #

你所有的setter方法里，都错误地声明了和类成员同名的局部变量，比如：

void HeartRates::setFirstName(string firstname) {
    string firstName = firstname; // 这里是创建了一个局部的firstName，和类成员没关系！
}

这个局部变量会覆盖类的成员变量，导致用户输入的姓名、出生日期根本没存到HeartRates对象里，所以后续调用get方法返回的都是默认值（或者未初始化的垃圾值）。

同样，第二个构造函数也犯了同样的错误：

HeartRates::HeartRates(std::string firstname, std::string lastname, int day, int month, int year) {
    string setFirstName(firstname); // 这不是调用setter，是创建局部变量！
    // ...其他同理
}

修正方式：

• Setter方法里去掉局部变量的类型声明，直接给类成员赋值：

  void HeartRates::setFirstName(string firstname) {
      firstName = firstname; // 直接赋值给类的成员变量
  }
  

• 构造函数要么直接给成员赋值，要么调用对应的setter：

  HeartRates::HeartRates(std::string firstname, std::string lastname, int day, int month, int year) {
      setFirstName(firstname);
      setLastName(lastname);
      setDayOfBirth(day);
      setMonthOfBirth(month);
      setYearOfBirth(year);
  }
  

• 默认构造函数用初始化列表给成员赋值（更规范）：

  HeartRates::HeartRates() : firstName("unknown"), lastName("unknown"), dayOfBirth(0), monthOfBirth(0), yearOfBirth(0) {}
  

2. 年龄计算逻辑错误 #

当前的getAge函数里，月份和日期的判断完全没起到作用，不管用户是否过了当年的生日，都直接返回当前年份 - 出生年份，这会导致年龄计算不准确。比如当前是2024年3月，用户生日是2000年4月，实际年龄是23，但你的代码会返回24。

修正后的年龄计算逻辑：

int HeartRates::getAge() {
    int currentYear, currentMonth, currentDay;
    cout << "Enter current year: " << endl;
    cin >> currentYear;
    cout << "Enter current month: " << endl;
    cin >> currentMonth;
    cout << "Enter current day: " << endl;
    cin >> currentDay;

    int age = currentYear - getYearOfBirth();
    // 如果当前月份小于出生月份，说明还没到生日，年龄减1
    if (currentMonth < getMonthOfBirth()) {
        age--;
    }
    // 如果月份相同，但当前日期小于出生日期，也减1
    else if (currentMonth == getMonthOfBirth() && currentDay < getDayOfBirth()) {
        age--;
    }
    return age;
}

3. 其他小问题优化 #

• getTargetHeartRate函数输出的是浮点数，但用int类型的maxHR计算会导致精度丢失，建议强制转换为double类型计算：

  void HeartRates::getTargetHeartRate(int maxHR) {
      double lower = static_cast<double>(maxHR) * 0.5;
      double upper = static_cast<double>(maxHR) * 0.85;
      cout << "Your target heart rate is between " << lower << " and " << upper << " bpm." << endl;
  }
  

• 把类的成员变量设为private，符合面向对象的封装原则，避免外部直接修改成员变量；
• main函数末尾加上return 0，符合C++程序的规范。

修正后的完整代码 #

HeartRates.h #

#include <string>
class HeartRates {
public:
    explicit HeartRates();
    HeartRates(std::string firstname, std::string lastname, int day, int month, int year);
    void setFirstName(std::string); 
    void setLastName(std::string); 
    void setDayOfBirth(int); 
    void setMonthOfBirth(int); 
    void setYearOfBirth(int); 
    std::string getFirstName() const; 
    std::string getLastName() const; 
    int getDayOfBirth() const; 
    int getMonthOfBirth() const; 
    int getYearOfBirth() const; 
    int getAge(); 
    int getMaxHeartRate(int); 
    void getTargetHeartRate(int); 
    void displayHeartRates(int); 
private:
    std::string firstName;
    std::string lastName;
    int dayOfBirth;
    int monthOfBirth;
    int yearOfBirth;
};

HeartRates.cpp #

#include <iostream>
#include "HeartRates.h"
using namespace std;

HeartRates::HeartRates() : firstName("unknown"), lastName("unknown"), dayOfBirth(0), monthOfBirth(0), yearOfBirth(0) {}

HeartRates::HeartRates(std::string firstname, std::string lastname, int day, int month, int year) {
    setFirstName(firstname);
    setLastName(lastname);
    setDayOfBirth(day);
    setMonthOfBirth(month);
    setYearOfBirth(year);
}

void HeartRates::setFirstName(string firstname) {
    firstName = firstname;
}

void HeartRates::setLastName(string lastname) {
    lastName = lastname;
}

void HeartRates::setDayOfBirth(int day) {
    dayOfBirth = day;
}

void HeartRates::setMonthOfBirth(int month) {
    monthOfBirth = month;
}

void HeartRates::setYearOfBirth(int year) {
    yearOfBirth = year;
}

string HeartRates::getFirstName() const {
    return firstName;
}

string HeartRates::getLastName() const {
    return lastName;
}

int HeartRates::getDayOfBirth() const {
    return dayOfBirth;
}

int HeartRates::getMonthOfBirth() const {
    return monthOfBirth;
}

int HeartRates::getYearOfBirth() const {
    return yearOfBirth;
}

int HeartRates::getAge() {
    int currentYear, currentMonth, currentDay;
    cout << "Enter current year: " << endl;
    cin >> currentYear;
    cout << "Enter current month: " << endl;
    cin >> currentMonth;
    cout << "Enter current day: " << endl;
    cin >> currentDay;

    int age = currentYear - getYearOfBirth();
    if (currentMonth < getMonthOfBirth()) {
        age--;
    } else if (currentMonth == getMonthOfBirth() && currentDay < getDayOfBirth()) {
        age--;
    }
    return age;
}

int HeartRates::getMaxHeartRate(int age) {
    return 220 - age;
}

void HeartRates::getTargetHeartRate(int maxHR) {
    double lower = static_cast<double>(maxHR) * 0.5;
    double upper = static_cast<double>(maxHR) * 0.85;
    cout << "Your target heart rate is between " << lower << " and " << upper << " bpm." << endl;
}

void HeartRates::displayHeartRates(int age) {
    cout << "Hello " << getFirstName() << " " << getLastName() << endl;
    cout << "Your DOB is " << getDayOfBirth() << "/" << getMonthOfBirth() << "/" << getYearOfBirth() << endl;
    cout << "Your age is " << age << " years old" << endl;
}

main.cpp #

#include <iostream>
#include "HeartRates.h"
using namespace std;
int main() {
    int d, m, y;
    string firstName, lastName;
    HeartRates heart;
    cout << "Please enter your first name: ";
    cin >> firstName;
    heart.setFirstName(firstName);
    cout << "Please enter your last name: ";
    cin >> lastName;
    heart.setLastName(lastName);
    cout << "What year were you born: ";
    cin >> y;
    heart.setYearOfBirth(y);
    cout << "What month were you born on: ";
    cin >> m;
    heart.setMonthOfBirth(m);
    cout << "What day were you born on: ";
    cin >> d;
    heart.setDayOfBirth(d);
    int age = heart.getAge();
    int maxHR = heart.getMaxHeartRate(age);
    heart.displayHeartRates(age);
    heart.getTargetHeartRate(maxHR);
    return 0;
}

这样修正后，程序应该能正确存储用户输入的数据，准确计算年龄和心率范围，输出符合预期了。

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