C++ Structs

struct structure_name
{
     // member declarations.
} 

struct Student
{
    char name[20];
     int id;
     int age;
}

s.id = 4;

#include <iostream>  
using namespace std;  
 struct Rectangle    
{    
   int width, height;    
    
 };    
int main(void) {  
    struct Rectangle rec;  
    rec.width=8;  
    rec.height=5;  
   cout<<"Area of Rectangle is: "<<(rec.width * rec.height)<<endl;  
 return 0;  
}  

Area of Rectangle is: 40

#include <iostream>  
using namespace std;  
 struct Rectangle    {    
   int width, height;    
  Rectangle(int w, int h)    
    {    
        width = w;    
        height = h;    
    }    
  void areaOfRectangle() {     
    cout<<"Area of Rectangle is: "<<(width*height); }    
 };    
int main(void) {  
    struct Rectangle rec=Rectangle(4,6);  
    rec.areaOfRectangle();  
   return 0;  
}  

Area of Rectangle is: 24