int i; /* a loop counter */
int num;  /* the number of readings to average */

int ticks;  /* the # of clock ticks returned for */
            /* a single reading */
int ticksAvg; /* the average of num readings */

void main(void) {
   num = 20;  /* set the number of readings to average */
   sonar_init();  /* initialize the sonar function */
                  /* must be called before sonar() */
   printf("press start\n");
   while(1) { /* loop continually */
      if(start_button()) {  /* take num readings every time */
                            /* start is pushed */
         ticksAvg = 0;  /* initialize to 0 */
         for(i=0;i<num;i++) { /* take num readings */
            ticks = sonar() / num;  /* dividing first then summing */
                                    /* will avoid an overflow error */
            if(ticks > 0) { /* occasionaly the sonar() function fails */
                            /* and returns a neg. value, discard it */
               ticksAvg += ticks; /* sum ticks to get average */
            }
         }
         printf("ticks = %d\n",ticksAvg); /* print the result */
      }
   }
}