Student Record & Registration using LinkList in C/C++

#include<iostream>
#include<conio.h>
#include<string>
#include<stdlib.h>  
using namespace std;

bool register_student(struct student *stud,struct list *ls);
double calculate_aggregiate(struct student *);
void addToList(struct student *stud, struct list *l);
void showList(struct student *stud, struct list *l);

struct student
{
char name[20];
int metric_marks, fsc_marks, entryTest_marks;
student *next;

};

struct list
{
char name[20];
double aggr;
list *next;

};


int main()
{
student *s;
s = (struct student *) malloc(sizeof(struct student));

struct list *ls;
ls = (struct list *) malloc(sizeof(struct list));
strcpy(ls->name, "");
ls->aggr = 0;
ls->next= NULL;
do
{
cout<<"Write 1 to Register a new student\n";
cout<<"Write 2 to Display lists of students registered\n";
cout<<"Write 3 to Quit\n";
 
int input;
cin>>input;
if (input == 1)
{
register_student(s, ls);

}
else if (input == 2)
{
showList(s, ls);
}
else if (input == 3)
exit(0);
cout<<"\n";
} while(1);

getch();
}

bool register_student(struct student *stud,struct list *ls)
{
student *s = stud;
cout<<"Write name of student\n";
cin>>s->name;
cout<<"Enter metric percentage\n";
cin>>s->metric_marks;
cout<<"Enter fsc percentage\n";
cin>>s->fsc_marks;
cout<<"Enter entry test percentage\n";
cin>>s->entryTest_marks;

double aggregiate;
aggregiate = calculate_aggregiate(s);
cout<<"aggregiate percentage is "<< aggregiate<<"\n";
if (aggregiate >= 70)
{
cout<<"Student registered in Electrical\n";
addToList(s,ls);
return true;
}
else if (aggregiate >= 60)
{
cout<<"Student registered in Mechanical\n";
addToList(s,ls);
return true;
}
else if (aggregiate >=50)
{
cout<<"Student registered in CSE\n";
addToList(s,ls);
return true;
}
else
{
cout<<"Sorry, the student can't be registered in engineering\n";
return false;
}

}

double calculate_aggregiate(struct student *stud)
{
student *s = stud;
double aggr;
aggr = s->metric_marks * 10/100  + s->fsc_marks * 50/100 + 
   s->entryTest_marks * 40/100;
        
return aggr;

}


void addToList(struct student *stud, struct list *l)
{
list *pointer = l;
while (pointer->next != NULL)
{
pointer = pointer->next;
} 
pointer->next = (struct list *) malloc(sizeof(struct list));
pointer = pointer->next;
strcpy(pointer->name , stud->name);
pointer->aggr = calculate_aggregiate(stud);
pointer->next = NULL;


}

void showList(struct student *stud, struct list *l)
{
list *pointer = l;
if (pointer->next == NULL)
cout<<"No student registered yet!\n";
else
{
cout<<"Students statistics are: \n";
while (pointer->next != NULL)
{
pointer = pointer->next;
cout<<"Name of student is: "<<pointer->name<<"\n";
cout<<"Aggregiate of student is: "<<pointer->aggr<<"\n";
if (pointer->aggr >= 70)
cout<<"Student registered in Electrical\n";
else if(pointer->aggr >=60)
cout<<"Student registered in Mechanical\n";
else
cout<<"Student registered in CSE\n";
cout<<"\n";
}
}
}