使成员成为嵌套类 [英] making a member fo a nested class

问题描述

#include"StdAfx.h"
#include<iostream>
#include<cstddef>
#include<ctime>
//#include<WinBase.h
using namespace std;

class college //outer class
{
	class student //inner class 1
	{
		int year,rollno;
		char *name,*stream;
		student *next,*prev;
	};
	class accounts //
	{
		time_t now;
		tm *ltm;
		int current_year;
		int current_month;
		int current_date;
		int current_hour;
		int current_minute;
		int current_sec;
		int semester_fees;
		int breakpoints[7][7];
		int amount;
	};
public:
	class linklist
	{
		student *start;
		student *temp;
		student *next;
		student *prev;
	public:
		linklist(char *name,char *stream,int year,int rollno)
		{
			student *ptr=new student();
			start=ptr;
			ptr->name=name;
			ptr->rollno=rollno;
			ptr->stream=stream;
			ptr->year=year;
			temp=start;
		}
		void append(char *name,char *stream,int year,int rollno)
		{
			student *ptr1=new student();
			ptr1->name=name;             //why? error
			ptr1->stream=stream;         //why error?
			ptr1->year=year;             //why error? 
			ptr1->rollno=rollno;         //why error?
			
		}
		char* current_name()
		{
			return temp->name;
		}
		char* current_stream()
		{
			return temp->stream;
		}
		int current_rollno()
		{
			return temp->rollno;
		}
		int current_year()
		{
			return temp->year;
		}
	};
};

int main()
{
	college::linklist l("bhawin","ecn",1991,123);

	return 0;
}

当我尝试访问学生班级成员时出错，为什么？

there is error when i try to access the member of student class, why?

推荐答案

您无法访问学生的私人成员类（默认类成员的可见性私有）。这是一个通用的 C ++ 规则（与嵌套类无关）。

你要么要

• 为 student 类成员（即 student 类本身中的get / set方法）提供访问器。
• 更改为 public 学生班级成员的可见性。
• 声明朋友需要访问学生班级成员的班级。

You cannot access private members of the student class (default visibility for class members is private). It is a general C++ rule (has nothing to do with nested classes).
You have either to

• Provide accessors for student class members (that is get/set methods in student class itself).
• Change to public the visibility of student class members.
• Declare friend the classes that need to access student class members.

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