Answer T7

#include <stdio.h>

struct Bulb
{
  int watts;
  int lumens;
};

/* function to print a Bulb */
void printBulb( struct Bulb* b )
{
  printf("watts = %d\tlumens = %d\n", b->watts, b->lumens );
}

/* function to decrease light output */
void dimBulb( struct Bulb* b )
{
  /* decrease output by 10 percent */
  b->lumens = (b->lumens*90)/100;
}

int main()
{
  struct Bulb bulbA = {100, 1710 };
  
  printBulb( &bulbA );         
  dimBulb( &bulbA );
  printBulb( &bulbA );
        
  return 0;
} 

The parameter for dimBulb() must be an address if the function is to make a permanent change to the data in main()'s bulbA.