#include <stdio.h>

struct BankAccount 	// I define struct BankAccount here for brevity
{   
  int   ID;
  float balance;
};

int main( int argc, char *argv[] )
{
  struct BankAccount john, mary, *p ;
          // p can store a reference to a struct BankAccount var

  john.balance = 500;
  mary.balance = 500;
  printf("j: %f  m:%f\n\n", john.balance, mary.balance); 

  /* -----------------------------------------------
     Update john.balance using reference variable
     ----------------------------------------------- */
  p = &john; // Now *p ≡ john
  (*p).balance = (*p).balance + 2000;    // Updates john.balance
  printf("j: %f  m:%f\n\n", john.balance, mary.balance); 

  /* -----------------------------------------------
     Update mary.balance using reference variable
     ----------------------------------------------- */
  p = &mary; // Now *p ≡ mary
  (*p).balance = (*p).balance + 9000;    // Updates mary.balance
  printf("j: %f  m:%f\n\n", john.balance, mary.balance); 
}