Question

#include <iostream>
#include "people.h"
#include "birthday.h"
#include <string>

int main(){
    std::string myname;
    int a;
    int b;
    int c;


    std::cout << " What is your name " << std::endl;
    std::getline(std::cin, myname);
    std::cout << "What month where you born " << std::endl;
    std::cin >> a;
    std::cout << "What day where you born " <<  std::endl;
    std::cin >> b;
    std::cout << "What year where you born in " << std::endl;
    std::cin >> c;
    birthday birthdayobjects(a ,b ,c);
    people peopleobjects(myname, birthdayobjects);
    peopleobjects.printInfo();
}

我有这样的main.cpp文件，其中有两个带有参数的构造函数，这些参数由用户输入。我想将此压缩为一个功能，以便主文件看起来像这样。

    #include <iostream>
    #include "people.h"
    #include "birthday.h"
    #include <string>
    #include "askquestions.h"

int main(){
    askquestions getquestions();
    birthday birthdayobjects(a ,b ,c);
    people peopleobjects(myname, birthdayobjects);
    peopleobjects.printInfo();
}

但是问题是当我尝试这样做时，在该范围内看不到变量。如果将变量放在ask-questions类中，则依赖输入的main函数中的类将无法获取参数。我尝试了extern，但它已编译但无法正常工作。当我尝试在main.cpp文件中将变量设置为全局变量时，这也不起作用。在这种情况下最好的选择是什么？

Answer 1

第一点

askquestions getquestions();

是错误的（它声明一个名为getquestions的函数不是变量），应该是

askquestions getquestions;

像这样设计您的askquestions类

class askquestions
{
public:
     askquestions();
     int geta() { return a; }
     int getb() { return b; }
     int getc() { return c; }
private:
     int a;
     int b;
     int c;
};

这三个getX方法称为 getters ，这是从类中获取信息的典型方式。

然后在您的主要功能中使用此类吸气剂

int main()
{
    askquestions getquestions;
    birthday birthdayobjects(getquestions.geta(), getquestions.getb(), getquestions.getc());
    ...
}

查看如何使用先前声明的getquestions变量调用getter方法。

Answer 2

askquestions没有理由成为班级。为此，您应该更喜欢一个自由函数，该函数返回一个birthday，或者最好返回一个people

例如

people askquestions()
{
    std::string myname;
    int month; // prefer descriptive names to single letters unless the single letter 
               // has a widely recognized meaning in the algorithm
    int day;
    int year;

    std::cout << " What is your name " << std::endl;
    std::getline(std::cin, myname);
    std::cout << "What month where you born " << std::endl;
    std::cin >> month;
    std::cout << "What day where you born " <<  std::endl;
    std::cin >> day;
    std::cout << "What year where you born in " << std::endl;
    std::cin >> year;

    return people(myname, birthday (month ,day , year));
}

用法：

int main(){
    people peopleobjects = getquestions();
    peopleobjects.printInfo();
}

想创建一个变量可供其他类使用的类

2 个答案: