[英]How do you have a struct as a private member in a class and creating a parameterized constructor/setter function for it?
I haven't seen questions about this so I hope this isn't a repeat, but I know you can have a struct as a private member of the class.我还没有看到关于这个的问题,所以我希望这不是重复,但我知道你可以拥有一个结构作为 class 的私有成员。 There seems to be no eloquent way to have a parameterized constructor with a struct as private member.
似乎没有 eloquent 方法可以将带有结构的参数化构造函数作为私有成员。 Then there becomes the problem of having a setter function for the struct private member.
然后就出现了为结构私有成员设置设置器 function 的问题。 There seems to be no way to access the struct members through a setter function within the one class.
似乎无法通过一个 class 中的设置器 function 访问结构成员。
The header file for the Book class图书 class 的 header 文件
// Book.h file
// Header file for the Book class
#ifndef BOOK_H
#define BOOK_H
#include <iostream>
#include "Date.h"
class Book {
private:
std::string m_ISBN;
std::string m_title;
std::string m_author;
Date m_date;
public:
// constructor
Book();
Book(std::string, std::string, std::string, Date);
void set_date(int, Month, int);
};
#endif
The header file for the Date struct Date 结构的 header 文件
// Date.h file
// Header file for the Date struct
#ifndef DATE_H
#define DATE_H
enum class Month {
jan = 1, feb, mar, april, may, june, july, aug, sep, oct, nov, dec, MAXMONTH
};
struct Date {
int m_year { 1800 };
Month m_month { Month::jan };
int m_day { 1 };
};
#endif
And then here's my cpp file然后这是我的 cpp 文件
// Book.cpp file
#include "Book.h"
Book::Book()
: m_ISBN { " " },
m_title { " " },
m_author { " " },
m_date {1800, Month::jan, 1 }
{
}
Book::Book(std::string ISBN, std::string title, std::string author, Date date)
: m_ISBN { ISBN },
m_title { title},
m_author { author },
m_date { date }
{
}
void Book::set_date(int year, Month month, int day) {
this->Date::m_year { year }; // error
this->Date::m_month { month }; // error
this->Date::m_day { day }; // error
}
The code works fine up until set_date
, but even before that point.该代码在
set_date
之前工作正常,但甚至在此之前。 If you create a Book object with parameters, the way you do it seems unintuitive Book one {"random_ISBN", "random_title", "random_author", { 1800, Month::jan, 3} };
如果您创建带有参数的 Book object,您的操作方式似乎不直观
Book one {"random_ISBN", "random_title", "random_author", { 1800, Month::jan, 3} };
Having these nest curly braces seems suboptimal.拥有这些嵌套花括号似乎不是最理想的。 You could create a Date struct and then pass that into it, but that seems wrong.
您可以创建一个 Date 结构,然后将其传递给它,但这似乎是错误的。
Replace代替
void Book::set_date(int year, Month month, int day) {
this->Date::m_year { year }; // error
this->Date::m_month { month }; // error
this->Date::m_day { day }; // error
}
with和
void Book::set_date(int year, Month month, int day) {
m_date.m_year = year;
m_date.m_month = month;
m_date.m_day = day;
}
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