Students using vectors subject average c++

#include <iostream>
#include <string>
#include <vector>

using namespace std;

vector <int> getGrades(vector<string> students,
vector<string> subjects);

vector<double> getStudentAverage(
vector<int> grades,int sub,int stu);

vector<double> getSubjectAverage(
vector<int>grades,int sub,int stu);

void printSubjectAverage(
vector<string>subjects,
vector<double>subjectAverage);

void printStudentAverage(
vector<string>students,
vector<double>studentAverage);

void printBestStudentAverage(
vector<string>students,
vector<double>studentAverage);


int main(){

vector <string>
students {
"Johnny", "Billy",
"Dave", "Sam", "Mike"},
subjects {
"Physics", "Math","Arabic",
"English", "History", "Biology"};

vector<int> grades;
vector<double>
studentAverage,
subjectAverage;

grades = getGrades(students,subjects);
studentAverage = getStudentAverage(grades,
subjects.size(),students.size());
subjectAverage = getSubjectAverage(grades,
subjects.size(),students.size());
printSubjectAverage(
subjects,
subjectAverage);
printStudentAverage(
students,
studentAverage);
printBestStudentAverage(
students,
studentAverage);

return 0;
}

vector <int>  getGrades(vector<string> students,
vector<string> subjects)
{
   int grade;
   vector <int> g;
  for ( auto e : students){
      cout<< e << endl;
     for(auto sb : subjects){
        cout<<sb<<endl;
        cin>>grade;
        g.push_back(grade);
    }
     cout<<"\n\n";
    }

return g;
}
/*
use i to control switch
reset i for each student
**/

vector <double>  getStudentAverage(
vector<int> grades,
int sub,int stu)
{
   vector<double> sum (stu);
   int i=0;
  for(auto g : grades){
        switch(i){
    case 0:
    sum.at(0)+=g;
    break;
    case 1:
     sum.at(1)+=g;
    break;
    case 2:
     sum.at(2)+=g;
    break;
    case 3:
    sum.at(3)+=g;
    break;
    case 4:
        sum.at(4)+=g;
    break;
     }//end switch
     i++;
    if(i>=sub)
       i=0;

 }
// create average
for(int i=0;i<sum.size();i++)
       sum.at(i)/=sub;

return sum;
}
/*
same reasioning as above
only this time it's using
subjects with the i controling
the switch
**/
vector<double> getSubjectAverage(
vector<int>grades,int sub,int stu)
{
  vector<double>sum(sub);
  int i=0;
     for(auto g : grades){
        switch(i){
    case 0:
    sum.at(0)+=g;
    break;
    case 1:
    sum.at(1)+=g;
    break;
    case 2:
    sum.at(2)+=g;
    break;
    case 3:
    sum.at(3)+=g;
    break;
    case 4:
    sum.at(4)+=g;
    break;
    case 5:
    sum.at(5)+=g;
    break;
     }//end switch
    i++;
    if(i>=sub)
       i=0;
   } //end for
for(int i=0;i<sum.size();i++)
    sum.at(i)/=stu;

return sum;
}

/*
 prints, they're matching
 sizes so use only one
 to control printing
 out both
**/

void printSubjectAverage(
vector<string>subjects,
vector<double>subjectAverage){

cout<<"\nSubject Average\n";
for(int i=0;i<subjects.size();i++){
      cout<<subjects.at(i)<<" ";
      cout<<subjectAverage.at(i)<<"\n";
    }
cout<<"\n";
}

void printStudentAverage(
vector<string>students,
vector<double>studentAverage){

cout<<"\nStudent Average\n";
for(int i=0;i<students.size();i++){
    cout<<students.at(i)<<" "
    <<studentAverage.at(i)<<"\n";
    }
cout<<"\n";
}

/*
got max number
needed a way to know
which student had that
number.

simple, loop check,
get student element number
on match, print it.
**/

void printBestStudentAverage(
vector<string>students,
vector<double>studentAverage){

double max = *max_element(studentAverage.begin(),
studentAverage.end());
int i=0;
for(auto m : studentAverage){
    if(max == m){
     cout<<students.at(i)<<" has the best "
     <<"average "<<" "<<max<<endl;
    }
      i++;
 }
cout<<"\n";
}