C++ struct assigning one structure to another

#include <iostream>
using namespace std;
#include <iomanip.h>
struct student/*from   w ww. j a  va  2s.  c  om*/
{
   char st_name[25];
   char grade;
   int age;
   float average;
};
void main()
{
   student std1 = {"Test", 'A', 13, 91.4};
   struct student std2, std3;          // Not initialized
   std2 = std1;             // Copies each member of std1
   std3 = std1;             // to std2 and std3.
   cout << "The contents of std2:\n";
   cout << std2.st_name << " " << std2.grade << " ";
   cout << std2.age << " " << setprecision(1) << std2.average << "\n\n";
   cout << "The contents of std3:\n";
   cout << std3.st_name << " " << std3.grade << " ";
   cout << std3.age << " " << std3.average << "\n";
   return;
}