How do you pass struct parameters in a method - c++

Question

I did not find anywhere the answer for my issue, I am pretty new to OOP so please give me mercy.
Okay so I have the following code:
class Group
{
public:
struct Student
{
char name[40],
int grades[5]};
}
Student s[10];
.....
private: double med(???)
{
.....
}
}
So where's ??? I want to have as parameters the grades of an individual student and return the average of them. I don't know how should I declare them, I tried in many ways but I get errors everytime.
Ty a lot

Answer 1

So you have a struct with parameters, like:
struct Student
{
std::string name;
std::array<int, 5> grades;
};
Since this is tagged C++, I chose to use a std::array<int, 5> rather than int[5].
In my opinion, Student should not be necessarily inside of Group, but I guess that's opinion based.
Now you have a Group which contains students:
struct Group
{
Group(std::vector<Student> students) :
_students{ std::move(students) }
{}
double med(/* ... */) const
{ /* ... */ }
std::vector<Student> _students; // C++ -> use std::vector
};
Say you want to pass the grades of a particular student as parameter of the function med, than you would simply do:
double Group::med(const std::array<int, 5>& grades) const
{ /* sum up grades, divide by 5, and return the result */ }
And you would call this function as follows:
Student paul{"Paul", {1,2,3,4,5}};
Group group({paul});
group.med(paul.grades);
As suggested in the comments, you might want to pass the name of a student instead of his/her grades:
double med(const std::string& name)
{
// find student
auto it = std::find_if(_students.begin(), _students.end(), [&name](const Student& student)
{
return student.name == name;
});
// if no student by that name
if (it == _students.end())
return -1.0;
// else
int sum{ 0 };
for (const auto& grade : it->grades)
{
sum += grade;
}
return static_cast<double>(sum)/(it->grades.size());
}
Here is a discussion about good C++ books.

Answer 2

Tyr this code Contains four avg() functions all are same but differ in how the functions are called.
#include<iostream>
#include<string.h>
using namespace std;
class Group
{
public:
struct Student
{
char name[40];
int grades[5];
}student;
double avg()
{
double sum=0;
for(int i=0;i<5;i++)
sum+=student.grades[i];
return (sum/5);
}
};
double avg(int *grade)
{
double sum=0;
for(int i=0;i<5;i++)
sum+=grade[i];
return (sum/5);
}
double avg(Group::Student stduent)
{
double sum=0;
for(int i=0;i<5;i++)
sum+=stduent.grades[i];
return (sum/5);
}
double avg(Group group)
{
double sum=0;
for(int i=0;i<5;i++)
sum+=group.student.grades[i];
return (sum/5);
}
int main()
{
Group group1;
strcpy(group1.student.name,"MyName");
for(int i=0;i<5;i++)
group1.student.grades[i]=5;
cout<<"Name:"<<group1.student.name<<endl;
cout<<"Avg:"<<avg(group1.student.grades)<<" "<<avg(group1.student)<<" "<<avg(group1)<<" "<<group1.avg();
return 0;
}
Output:
Name:MyName
Avg:5 5 5 5
Process returned 0 (0x0) execution time : 0.379 s
Press any key to continue.
You may leave the structure unnamed like
struct
{
char name[40];
int grades[5];
}student;
If you delete the function and function call from the code
double avg(Group::Student stduent)
{
double sum=0;
for(int i=0;i<5;i++)
sum+=stduent.grades[i];
return (sum/5);
}