To convert multi level to hierarchy inheritance in c++ - c++

Question

When I tried to convert it the class result can't get the data from class marks even if I made the data variables of marks public I don't know why. I also declared a object of class marks in result and then tried to access it but failed again I am new to coding so don't know all the syntax correctly your help will be of great use
#include <string.h>
#include <iostream>
using namespace std;
class student {
private:
int rl;
char nm[20];
public:
void read();
void display();
};
class marks : public student {
protected:
int s1;
int s2;
int s3;
public:
void getmarks();
void putmarks();
};
class result : public marks {
private:
int t;
float p;
char div[10];
public:
void process();
void printresult();
};
void student::read() {
cout << "enter Roll no and Name " << endl;
cin >> rl >> nm;
}
void student::display() {
cout << "Roll NO:" << rl << endl;
cout << "name : " << nm << endl;
}
void marks ::getmarks() {
cout << "enter three subject marks " << endl;
cin >> s1 >> s2 >> s3;
}
void marks ::putmarks() {
cout << "subject 1:" << s1 << endl;
cout << "subject 2 :" << s2 << endl;
cout << "subject 3:" << s3 << endl;
}
void result::process() {
t = s1 + s2 + s3;
p = t / 3.0;
p >= 60 ? strcpy(div, "first")
: p >= 50 ? strcpy(div, "second")
: strcpy(div, "third");
}
void result::printresult() {
cout << "total = " << t << endl;
cout << "per = " << p << "%" << endl;
cout << "div = " << div << endl;
}
int main(){
result x;
x.read();
x.getmarks();
x.process();
x.display();
x.putmarks();
x.printresult();
}

Answer 1

#include<iostream>
#include<string.h>
using namespace std;
class marks // parent class
{
protected:
int s1;
int s2;
int s3;
public:
void getmarks();
void putmarks();
};
class student : public marks // child class
{
private:
int rl;
char nm[20];
public:
void read();
void display();
};
class result : public marks// child class
{
private:
int t;
float p;
char div[10];
public:
void process();
void printresult();
};
void student::read()
{
cout<<"enter Roll no and Name "<<endl;
cin>>rl>>nm;
}
void student:: display()
{
cout <<"Roll NO:"<<rl<<endl;
cout<<"name : "<<nm<<endl;
}
void marks ::getmarks()
{
cout<<"enter three subject marks "<<endl;
cin>>s1>>s2>>s3;
}
void marks ::putmarks()
{
cout <<"subject 1:"<<s1<<endl;
cout<<"subject 2 :"<<s2<<endl;
cout <<"subject 3:"<<s3<<endl;
}
void result::process()
{
t= s1+s2+s3;
p = t/3.0;
p>=60?strcpy(div,"first"):p>=50?strcpy(div, "second"): strcpy(div,"third");
}
void result::printresult()
{
cout<<"total = "<<t<<endl;
cout<<"per = "<<p<<"%"<<endl;
cout<<"div = "<<div<<endl;
}
int main()
{
result x;
student y;
y.read();
x.getmarks();
x.process();
y.display();
x.putmarks();
x.printresult();
}