save.c
======
/* ================================================================

   Program to sort a sequence of positive integers termianted
   by a negative number. First a binary search sequence tree
   is constructed then the BSST is traversed in in-order fashion
   and the sorted list is printed.
   Also, saves the nodes in binary format on a file. Compile as
       gcc -ansi inpfile.c  -o objfile

   Prabu 3/15/94

   ================================================================ */

#include	<stdio.h>

#define  FNAMELEN  15     /* maximum length of the filename */

struct node
{
  int info;
  struct node *left;   /* left child */
  struct node *right;  /* right child */
};

const int nodesize = sizeof(struct node); /* in bytes */

int getfile(char *message, FILE **fp, char *mode) /* get the file and open it */
{
  char filename[FNAMELEN + 1];
  int i;
  printf("%s filename : ",message);
  scanf("%s",filename);
  if ((*fp = fopen(filename,mode)) == NULL) {
    printf("can't open %s \n",filename);
    return(-1);
  }
  return(0);
}

void insert(struct node *p, struct node **r)  /* insert node p in the tree */
{
  if (*r == NULL)
    *r = p;
  else
    if (p -> info < (*r)->info)
         insert(p, &(*r)->left);
    else insert(p, &(*r)->right);
  return;
}

void inorder(struct node *r) /* print the integers in sorted form */
{
  if (r != NULL)
  {
    inorder(r->left);
    printf(" %d ", r->info);
    inorder(r->right);
  }
  return;
}

void preordsave(struct node *r, FILE **f)
/* save the node in binary format on the file  -- preorder fashion */
{
  if (r != NULL)
  {
    if (!fwrite(r, nodesize, 1, *f)) {
	printf("Writing to the binary file failed .\n");
	exit(1);
    }
    if (r->left)
      preordsave(r->left, f);
    if (r->right)
      preordsave(r->right, f);
  }
  return;
}

main()
{
  struct node *root, *p;
  int n;
  FILE *fp;

  root = NULL;
  printf("Input sequence of integers & terminate by a negative value \n");
  scanf("%d", &n);
  while (n >= 0)
  {
    p = (struct node *) malloc(sizeof(struct node));    /* make a new node */
    p->info = n;
    p->left = p->right = NULL;
    insert(p, &root);
    scanf("%d", &n);
  }
  printf("\nSorted numbers are :\n");
  inorder(root);
  printf("\n\n");

  if (getfile("Output",&fp,"wb") < 0)
    return;

  preordsave(root, &fp);
  printf("This binary search sequence tree is saved in the file \n\n");
}


Execution
=========
Input sequence of integers & terminate by a negative value 
 45  67  32  58  25  50  60  -4

Sorted numbers are :
 25  32  45  50  58  60  67 

Output filename : number.bin
This binary search sequence tree is saved in the file