Problem with loop

[krutuk]

Hello, I did this function in main() and it works. Yet now I want to do it through the functions and I have a problem and don't know what to do. After execution the fucntion assigns the last value to all.
Here is the code done in main():

#include <iostream>
#include <string>
#include <sstream>

#define Mark 5
using namespace std;

struct sStud{
	string Name;
	int Group;
	int Ses[Mark];
};

int main()
{
	int i, n, t, j;
	double res[10];	
	string mystr;
	
	cout<<"Enter number of students: ";
	cin>>i;
	
	sStud st[i];
	
	for(n=0; n<i; n++){
		cin.get();		
		cout<<"Enter student's name: ";
		getline(cin,st[n].Name);
		cout<<"Enter student's group: ";
		getline(cin,mystr);
		stringstream(mystr)>>st[n].Group;
		cout<<"Enter 5 student's marks: ";
		for(t=0; t<Mark; t++){
			cin>>st[n].Ses[t];
		}
	}
	
	cout<<endl;
	cout<<"Students with average mark more then 4.0:"<<endl;
	for(n=0; n<i; n++){
		if((res[n]=(double)(st[n].Ses[0]+st[n].Ses[1]+st[n].Ses[2]+st[n].Ses[3]
			+st[n].Ses[4])/5)>=4){
			cout<<st[n].Name<<endl;
			cout<<"Group ES-"<<st[n].Group<<endl;
		}
	}
	if(res[0]<=4 && res[1]<=4 && res[2]<=4 && res[3]<=4 && res[4]<=4){
		cerr<<"No one student with average mark more then 4.0"<<endl;
	}

	double temp, temp_a;
	string temp_n;
	cout<<endl;
	cout<<"The list of student ordered by group's take off:"<<endl;	
	for(n=0; n<i; n++){
		for(j=0; j<i-1; j++){
			if(st[j].Group>st[j+1].Group){			
				temp_n=st[j].Name;				
				temp=st[j].Group;
				temp_a=res[j];
				st[j].Name=st[j+1].Name;
				st[j].Group=st[j+1].Group;
				res[j]=res[j+1];
				st[j+1].Name=temp_n;
				st[j+1].Group=temp;
				res[j+1]=temp_a;
			}
		}
	}
	for(n=0; n<i; n++){
		cout<<"Name: "<<st[n].Name<<endl;
		cout<<"Group: ES-"<<st[n].Group<<endl;
		cout<<"Average mark: "<<res[n]<<endl;
	}

	return 0;
}

And here is the code with problems:

#include <iostream>
#include <string>
#include <sstream>

#define Mark 5
using namespace std;

struct sStud{
	string Name;
	int Group;
	int Ses[Mark];
};

void input(int, sStud*);
double average(double*, sStud*, int);

void input(int i, sStud *p)
{
	int n, t;
	string mystr;	
		
	for(n=0; n<i; n++){
		cin.get();
		cout<<"Enter student's name: ";
		getline(cin,p->Name);
		cout<<"Enter student's group: ";
		getline(cin,mystr);
		stringstream(mystr)>>p->Group;
		cout<<"Enter 5 student's marks: ";
		for(t=0; t<Mark; t++){
			cin>>p->Ses[t];
		}
	}
}

double average(double *a, sStud *p, int i)
{
	int n;
	double res[10];

	a=&res[10]; //I don't know where I should point to array here or
	cout<<endl;
	cout<<"Students with average mark more than 4.0:"<<endl;
	for(n=0; n<i; n++){
		if((res[n]=(double)(p->Ses[0]+p->Ses[1]+p->Ses[2]+p->Ses[3]+p->Ses[4])/5)
			>=4.0){
			cout<<p->Name<<endl;
			cout<<"Group ES-"<<p->Group<<endl;
		}
	}
	cout<<res[0]<<", "<<res[1]<<", "<<res[2]<<", "<<res[3]<<", "<<res[4]<<endl;
	if(res[0]<=4 && res[1]<=4 && res[2]<=4 && res[3]<=4 && res[4]<=4){
		cerr<<"No one student with average mark more then 4.0"<<endl;
	}
		
	return *a;
}

int main()
{
	int i, n, t;
	double *a, res[10];
	sStud *p, st;
	
	cout<<"Enter number of students: ";
	cin>>i;	
	a=&res[10]; //here
	p=&st;
	input(i,p);
	average(a,p,i);

	return 0;
}

[krutuk]

I don't know what should I do at all. Is mistake in body of that function or this function is totaly wrong or the declaration in main() is wrong? Please, someone give me some direction.

[abhishekm71]

it seems you are not changing the pointer p while reading or calculating averages. the same pointer p gets overwritten while
for(t=0; t<Mark; t++){
cin>>p->Ses[t];
}
and the average function repeatedly checks the same pointer's value p->ses[].

Also, the avergae function is supposed to return a value but no variable is assigned to it while calling.

[krutuk]

About return I chenged. Unfortunetly, I still cann't do this function.

[abhishekm71]

there is confusion in your pointer assignments as I said earlier. You are trying to store the data of all the students in the same pointer variable. That's why its value is getting over-written. A different variable should store each student's data.
look at some examples of pointer assignments and usage.