/* This program is from lab 5, meant to demonstrate how to read in
   from a file and how to write output to a file.  It reads in the
   Mercedes used car prices data set, and writes out the mean price by
   model. */

/* gcc -o carsexample.exe carsexample.c */

#include<stdio.h>

#define NCASES 54
#define NMODELS 5

main(){
  int i, j;                          /* indices, counters */
  int casenum, age, mile, vend;      /* variables we don't care about */
  int price[NCASES];                 /* prices of the cars */
  int model[NCASES];                 /* model numbers of the cars */
  double priceave[NMODELS];          /* average price by model */
  int modelcount[NMODELS];           /* number of cases by model */
  FILE *fp;                          /* file pointer for input/output */
  
  fp = fopen("mercedes.dat","r");    /* open file for reading */

  for(i=0; i<NCASES; i++) {
    fscanf(fp,"%d %d %d %d %d %d", &casenum, &price[i], &model[i],
	   &age, &mile, &vend);      /* read in data */
    if(i==1) printf("%d %d %d %d %d %d\n", casenum, price[i], model[i],
	   age, mile, vend);         /* print out second case just to check */
  }
  fclose(fp);

  for(j=0; j<NMODELS; j++) {
    priceave[j] = 0.0;                          /* initialize average */
    modelcount[j] = 0.0;                        /* initialize count */
  }

  for(i=0; i<NCASES; i++) {
    priceave[model[i]] += price[i];             /* sum price by model */
    modelcount[model[i]]++;                     /* count by model */
  }

  fp = fopen("mercedes.out","w");               /* open file for writing */

  for(j=0; j<NMODELS; j++) {
    priceave[j] /= modelcount[j];               /* compute average */
    fprintf(fp,"%g  ",priceave[j]);
  }
  fprintf(fp,"\n");
  
  fclose(fp);

}