【发布时间】：2021-01-02 19:47:22
【问题描述】：
我正在创建一个具有不同功能的结构的 STL 列表。一切正常，除了当我尝试添加一个“朋友”时，计算出的年龄只是一堆数字。我认为问题出在 computeAge 函数或 addFriend 函数本身，但我看不出它们有什么问题。
*为简单起见编辑代码
程序：
#include<iostream>
#include<iomanip>
using namespace std;
#include<fstream>
#include<string>
#include<list>
#include<algorithm>
struct friendDat
{
string fName;
string lName;
int birthYear;
int birthMonth;
int birthDay;
char sex;
int age;
string dayBorn;
string season;
int todayYear;
int todayMonth;
int todayDay;
string name;
bool operator < (const friendDat& f)
{
if (f.age > age)
return true;
else
return false;
}
};
typedef list<friendDat> friends;
typedef friends::iterator it_f;
void getFriends(friends& f, friendDat element);
int computeAge(friendDat element);
string computeDayBorn(friendDat element);
string computeSeason(friendDat element);
void printFriends(friends f);
void addFriend(friends& f);
int main()
{
friendDat element;
friends f;
getFriends(f, element);
addFriend(f);
printFriends(f);
system("pause");*/
return 0;
}
void getFriends(friends& f, friendDat element)
{
ifstream infile;
cout << "Enter the numerical year(20XX), month, and day: ";
cin >> element.todayYear >> element.todayMonth >> element.todayDay;
cout << endl;
string season;
infile.open("friends.dat");
while (!infile.eof())
{
infile >> element.fName >> element.lName >> element.birthYear >> element.birthMonth >> element.birthDay >> element.sex;
element.age = computeAge(element);
element.dayBorn = computeDayBorn(element);
element.season = computeSeason(element);
f.push_back(element);
}
f.pop_back();
infile.close();
}
void addFriend(friends& f)
{
friendDat element;
cout << "Please enter the first name: " << endl;
cin >> element.fName;
cout << "Please enter the last name: " << endl;
cin >> element.lName;
cout << "Please enter the birth year: " << endl;
cin >> element.birthYear;
cout << "Please enter the birth month: " << endl;
cin >> element.birthMonth;
cout << "Please enter the birth day: " << endl;
cin >> element.birthDay;
cout << "Please enter the sex: " << endl;
cin >> element.sex;
element.age = computeAge(element);
element.dayBorn = computeDayBorn(element);
element.season = computeSeason(element);
f.push_back(element);
}
void printFriends(friends f)
{
for (it_f it = f.begin(); it != f.end(); it++)
{
cout << it->fName << " " << it->lName << " " << it->birthYear << " " << it->birthMonth << " "
<< it->birthDay << " " << it->sex << " " << it->age << " " << it->dayBorn << " " << it->season << endl;
}
}
int computeAge(friendDat element)
{
int todayYear = element.todayYear;
int todayMonth= element.todayMonth;
int todayDay = element.todayDay;
int age = todayYear - element.birthYear;
if (todayMonth < element.birthMonth)
age--;
if (todayMonth == element.birthMonth && todayDay < element.birthDay)
age--;
return age;
}
string computeDayBorn(friendDat element)
{
int d = element.birthDay;
int m = element.birthMonth;
int y = element.birthYear % 100;
int c = element.birthYear / 100;
if (m == 1 || m == 2)
{
m += 12;
y--;
}
int D = (d + (m + 1) * 26 / 10 + y + y / 4 + c / 4 + 5 * c) % 7;
if (D == 0) return "Saturday";
else if (D == 1)return "Sunday";
else if (D == 2)return "Monday";
else if (D == 3)return "Tuesday";
else if (D == 4)return "Wednesday";
else if (D == 5)return "Thursday";
else if (D == 6)return "Friday";
return "impossible";
}
string computeSeason(friendDat element)
{
int bMonth = element.birthMonth;
int bDay = element.birthDay;
string season = "";
if (bMonth == 12 || bMonth == 1 || bMonth == 2)
season = "Winter";
if (bMonth == 4 || bMonth == 5)
season = "Spring";
if (bMonth == 7 || bMonth == 8)
season = "Summer";
if (bMonth == 10 || bMonth == 11)
season = "Fall";
if (bMonth == 3 && bDay >= 21)
season = "Spring";
if (bMonth == 3 && bDay < 21)
season = "Winter";
if (bMonth == 6 && bDay >= 21)
season = "Summer";
if (bMonth == 6 && bDay < 21)
season = "Spring";
if (bMonth == 9 && bDay >= 21)
season = "Fall";
if (bMonth == 9 && bDay < 21)
season = "Summer";
return season;
}
friends.dat 文件：
Friend One 1998 8 23 M
Friend Two 2002 7 10 F
Friend Three 2001 5 3 M
Friend Four 2001 10 6 F
Friend Five 1999 1 10 M
Friend Six 2000 12 1 F
输出：
Enter the numerical year(20XX), month, and day: 2020 9 8
Please enter the first name:
REeeee
Please enter the last name:
ahhhh
Please enter the birth year:
1990
Please enter the birth month:
2
Please enter the birth day:
23
Please enter the sex:
F
Friend One 1998 8 23 M 22 Sunday Summer
Friend Two 2002 7 10 F 18 Wednesday Summer
Friend Three 2001 5 3 M 19 Thursday Spring
Friend Four 2001 10 6 F 18 Saturday Fall
Friend Five 1999 1 10 M 21 Sunday Winter
Friend Six 2000 12 1 F 19 Friday Winter
REeeee ahhhh 1990 2 23 F -858995451 Friday Winter
【问题讨论】：
-
调试器是最好的程序员生产力工具之一。使用调试器，您可以以您的速度浏览您的程序并观察程序的实际运行情况。这真的可以帮助您了解真正发生的事情。 “逐步”完成程序并留意意外情况。意外通常是一个错误
-
struct friendDat-- 你真的应该在其中一个被创建时初始化变量（有一个默认的构造函数）。现在，friendDat f;从一开始就不应该有奇怪或未知的值。 -
请花一些时间查看the help pages，接受SO tour，阅读How to Ask，以及this question checklist。请不要忘记minimal reproducible example 的 mininal 部分。
-
"我认为问题出在 computeAge 函数或 [...]" -- 你有一个假设。那很好。下一步：检验假设。单独测试
computeAge。定义几个friendDat对象（在代码中，不基于用户输入）并查看computeAge为每个对象返回什么。如果返回了错误的东西，你大约 90% 的方法是到达 minimal reproducible example。如果computeAge签出，您可以继续进行其他假设。 （单独测试。） -
另外，一个好的问题不会满足于像“只是一堆数字”这样的模糊描述。这是介绍问题的好方法，但在某些时候，您应该给出具体的预期和实际观察结果。 （如果您需要输入，也应该指定，但更好的做法是在示例代码中不要求用户输入。）