/* File: bubble4.c

   Bubblesort
   This one uses lots of functions and
   reads input from a file.
*/

#include <stdio.h>
#include <stdlib.h>

#define A_SIZE 100

void swap(int *ptr1, int *ptr2) ;
void PrintArray(int A[], int size) ;
void BubbleSort(int A[], int size) ;
int ReadArray(int A[], char fname[], int max_size) ;

int main() {

   int A[A_SIZE], n ;

   n = ReadArray(A, "data25.txt", A_SIZE) ;
   if ( n > 0 ) {
      printf("Read in %d numbers into array A[].\n", n) ;
   } else {
      printf("No numbers read into array A[]. Missing file??\n") ;
      return 0 ;
   }

   printf("Before sorting: ") ;
   PrintArray(A, n) ;

   BubbleSort(A, n) ;

   printf("After sorting:  ") ;
   PrintArray(A, n) ;

   return 0 ;
}


void BubbleSort(int A[], int size) {

   int i, j ;

   for (i = 0 ; i < size - 1 ; i++) {

       for (j = 0 ; j < size - i - 1 ; j++) {

          if (A[j] > A[j+1]) {
             swap(&A[j], &A[j+1]) ;
          }
       }
   }
   
}


void PrintArray (int A[], int size) {
   int i ;

   for  ( i = 0 ; i < size ; i++ ) {
      printf("%2d ", A[i]) ;
   }
   printf("\n") ;

}


void swap(int *ptr1, int *ptr2) {
   int temp ;

   temp = *ptr1 ;
   *ptr1 = *ptr2 ;
   *ptr2 = temp ;
}


/* ReadArray

   Opens the file specified by fname and reads
   integers into array A[], but not more than
   max_size items.

   Return value:
     positive number = # of integers read
     0 = empty file
     negative number = error encountered
   
*/

int ReadArray(int A[], char *fname, int max_size) {

   FILE *iFile ;
   int i, r, input ;

     // open fname for reading
    iFile = fopen(fname, "r") ;

     // open successful?
    if (iFile == NULL) {  
       return -1 ;
    }

    i = 0 ;
    while(1) {
       r = fscanf(iFile, "%d", &input) ;

       // end-of-file or not a number?
       if (r <= 0) {
          break ;
       }

       // store new number
       A[i] = input ;
       i++ ;

       // reached end of file?
       if (i == max_size) {
          // fprintf(stderr, "Array limit reached.\n") ;
          break ;
       }

       // This shouldn't ever happen!
       if (i > max_size) {
          fprintf(stderr, "Somehow, i > max_size!\n") ;
          abort() ;
       }
    }

    fclose(iFile) ; 
    return i ;
}