C++ struct Structure input with student data passed to functions

#include <iostream>
using namespace std;
#include <string.h>
#include <stdio.h>
#include <iomanip.h>
struct students fill_structs(struct students student_var);
void pr_students(struct students student_var);
struct students                     // A global structure.
{
   char name[25];
   int age;// w w w  . java  2  s.co  m
   float average;
};                           // No memory reserved.
void main()
{
   students student1, student2;     // Defines two local variables.

   student1 = fill_structs(student1);         
   student2 = fill_structs(student2);
   // Print the data.
   cout << "\n\nHere is the student information you";
   cout << " entered:\n\n";
   pr_students(student1);   
   pr_students(student2);  
   return;
}
struct students fill_structs(struct students student_var)
{
   fflush(stdin);    // Clears input buffer for next input.
   cout << "What is student's name? ";
   gets(student_var.name);
   cout << "What is the student's age? ";
   cin >> student_var.age;
   cout << "What is the student's average? ";
   cin >> student_var.average;
   return (student_var);
}
void pr_students(struct students student_var)
{
   cout << "Name:    " << student_var.name << "\n";
   cout << "Age:     " << student_var.age << "\n";
   cout << "Average: " << setprecision(2) << student_var.average << "\n";
   return;
}