c programming project

I've written this program, accessing a binary file and then comparing the data and writing to a new file, however the program on msdos does not work. I can't find the errors. Please Help.

/**************************************************************************/
/*This program is written for Zenith Paints Co. to provide a solution        */
/*The new sorted file from program two is used to update a line sequential*/
/*master file and this program will create a new master file.                  */
/*reference is made to an indexed sequential stock master file for price  */
/*information. A header is used to access this information called 'isam.h'*/
/*Any invalid transactions are then printed onto an error report.              */
/**************************************************************************/


#include<stdio.h>
#include<stdlib.h>
#include<conio.h>
#include<string.h>
#include<ctype.h>
#include<time.h>
#include<math.h>
#include "a:isam.h"      /*a header file storing stock data*/
#include"a:printer.h"

#define SIZE sizeof(struct master)
#define ISSUE struct I_R
#define DELREC struct deletion
#define CREREC struct create
#define SIZE_U sizeof(union valid)
#define PRINT "LPT1"
#define TRUE 1
#define FALSE 0
#define LASTCODE "ZZZZZ" /*ensures that if one file finishes first
the other one will continue to be processed*/


/*declare structures and union to hold the customer details*/
/*These structures are determined by the file specifications*/

struct stock                        /*structure held on header file*/
{
      char cust_code[6],
            cust_name[21],
            cust_add[61];
      float cust_bal;
      long credit_limit;
      int year,
            month,
            day;
} ;
struct stock new_s;

struct master                  /*structure held on master file*/
{
      char cust_code[6],
            cust_name[21],
            cust_add[61];
      float cust_bal;
      long credit_limit;
      int year,
            month,
            day;
};

struct I_R                        /*The structure for issue/receipt record*/
{
            char rec_type,
                  cust_code[6],
                  part_num[7],
                  iss_rec_qty[5];
            };

      struct deletion            /*The structure for delete record*/
            {
            char rec_type,
                  cust_code[6];
            };
            
      struct create            /*The structure for create record*/
            {
            char rec_type,
                  cust_code[6],
                  cust_name[21],
                  cust_add[61],
                  cust_bal[10],
                  cust_limit[8];
            };

union valid                        /*Union to hold all three structures*/
{
      ISSUE i;
      DELREC d;
      CREREC c;
};

/*********************************************************************/
/*Global declarations.                                                                         */
/*********************************************************************/

struct tm *todays_date;
time_t calendar_time;

/*declare function prototypes and theire names indicate*/
/*their purpose*/
void store_new(FILE *fp, struct master temp);
void print_headings(FILE *out_prn);
void error(FILE *out_prn, union valid u, int i);

/*********************************************************************/
/*      coding for solution                                                                         */
/*********************************************************************/

void main()
{

FILE *cp, *sort, *out_prn, *new_fp; /*file pointers for the four file*/
struct master temp;                              /*structure variable*/
union valid u;                                    /*union to hold the structures       */
int compare, records=0;                        /*compare variable to hold comaprison of*/
                                                      /*two structure*/                  
char ch;
char cust_code[4];                              /*to hole the customer code*/
float  total=0;
RECORD_DATA *stock_rec;      

calendar_time = time(NULL);
todays_date = localtime(&calendar_time);

                  /*to access the header file stock details*/


      if((out_prn=fopen(PRINT,"wt"))==NULL)
      {
            fprintf(stderr,"Error cannot open\n");/*if file does not open then exit*/
            exit(1);
      }

      if((cp=fopen("A:Custmast.dat","rb"))==NULL)
      {
            fprintf(out_prn,"Error cannot open\n");/*if file does not open then exit*/
            exit(1);
      }

if((sort=fopen("a:sort.dat","rb"))==NULL)
      {
            fprintf(out_prn,"Error cannot open sort\n");/*if file does not open then exit*/
            exit(1);
      }
      

if((new_fp=fopen("A:new.dat","wb+"))==NULL)
      {
            fprintf(stderr, "Error cannot open\n");/*if file does not open then exit*/
            exit(1);
      }


      print_headings(out_prn);                              /*declare fundion to print headings*/
            

            if(fread(&u,SIZE_U, 1, sort)!=1)
            {
                  fprintf(stderr, "Unable to read sort file\n");/*if file does not open then exit*/
                  exit(1);
            }
                        /*read first record from sorted file*/
            if(fread(&temp, SIZE, 1, cp)!=1)                        /*read first record from master file*/
            {
                  fprintf(stderr, "unable to read master file\n");/*if file does not open then exit*/
                  exit(1);
            }
                  /*copy 'ZZZZZ' to customer code to compare*/
                  /*if last record*/
      strcpy(u.i.cust_code, LASTCODE);

      while(strcmp(u.i.cust_code, LASTCODE)!=0 ||
       strcmp(temp.cust_code, LASTCODE)!=0)

      {
            /*store value in compare*/
             compare=strcmp(u.i.cust_code, temp.cust_code);

            /*there are a few possibilities here as */
             /*if the answer is yes than a check is      */
             /*done for the record type before a new */
             /*record is read*/

       if(compare<0)
       {
            
             ch=u.i.rec_type;
             ch=toupper(ch);

                  if(ch=='C')
                        store_new(new_fp, temp);
            
                  else
                        if(ch=='I'||ch=='R'||ch=='D')
                  error(out_prn,u, 1);

            if(fread(u.i.cust_code, SIZE_U, 1, sort)!=1)
            {
                  /*if eof occurs store lastcode in cust_code*/
            strcpy(u.i.cust_code, LASTCODE);
            } /*end if*/

       }/*end if*/

       if(compare>0)
       {
             store_new(new_fp, temp);
             if(fread(&temp, SIZE_U, 1, cp)!=1)
            {
      
            /*if eof occurs store lastcode in cust_code*/

            strcpy(u.i.cust_code, LASTCODE);
            } /*end if*/
             
       } /*end if*/


       if(compare==0)
       {
            
            ch=u.i.rec_type;
             ch=toupper(ch);

             switch(ch)
             {
                   case 'I':
                   case 'R':
                         
                               if((stock_rec=search_file(cust_code))!=NULL)
                              
                               {                                                              
                                     total=atoi(u.i.iss_rec_qty) * stock_rec->price;
                               }       
                                     if(ch=='I')
                                           temp.cust_bal+=total;
                                     else
                                           if(ch=='R')
                                          temp.cust_bal-=total;
                              
                                          else
                                     fprintf(out_prn,"Error in I\n");

                        
                        if(fread(&u, SIZE_U, 1, sort)!=1)
                              {
      
            /*if eof occurs store lastcode in cust_code*/

                              strcpy(u.i.cust_code, LASTCODE);
                              } /*end if*/
                                    store_new(new_fp, temp);

                               break;

                   case 'D':
                                       if(temp.cust_bal!=0)
                                                fprintf(out_prn,"Error in D\n");
                        if(fread(&u, SIZE_U, 1, sort)!=1)
                              {
      
            /*if eof occurs store lastcode in cust_code*/

                              strcpy(u.i.cust_code, LASTCODE);
                              } /*end if*/
                        else
                                       //eof1=readfile(sort);
                               if(fread(&u, SIZE_U, 1, sort)!=1)
                                    {
      
            /*if eof occurs store lastcode in cust_code*/

                                          strcpy(u.i.cust_code, LASTCODE);
                                    } /*end if*/
                                          if( fread(&temp, SIZE, 1, cp)!=1)
                                          {
      
            /*if eof occurs store lastcode in cust_code*/

                                                strcpy(temp.cust_code, LASTCODE);
                                          } /*end if*/
                                            

                         break;
                   case 'C': error(out_prn,u, 2);
                        if(fread(&u, SIZE_U, 1, sort)!=1)
                              {
      
            /*if eof occurs store lastcode in cust_code*/

                              strcpy(u.i.cust_code, LASTCODE);
                              } /*end if*/
                         

                         break;

            
                   default: break;
                  }/*end switch*/

            } /*end if*/
records++;
fflush(stdin);

}/*end while till eof*/

            fclose(new_fp);
             fclose(out_prn);
             fclose(sort);
             fclose(cp);
             
} /*end main*/

/*********************************************************************/
/*store_new()                                                                               */
/*Parameter:      new_fp. A pointer to the new file                              */
/*                        temp.      structure in old master file                        */
/*                                                                                                      */
/*                        Return:            none.                                                       */
/*                                                                                                       */
/*  A function that will use live local time and date each time the */
/*old data is stored into the new structure and then written to the      */
/*new file                                                                                          */      
/*********************************************************************/


void store_new(FILE *new_fp, struct master temp)
{
      
      int loop=0;
      struct tm today;
      time_t time_in_secs;
      time_in_secs = time(NULL);
      today = *localtime(&time_in_secs);

      strcpy( new_s.cust_name,temp.cust_name);
      strcpy(new_s.cust_add,temp.cust_add );
      strcpy(new_s.cust_code, temp.cust_code );
      new_s.cust_bal=temp.cust_bal;
      new_s.credit_limit=temp.credit_limit;

      new_s.year=today.tm_year;
      new_s.month=today.tm_mon+1;
      new_s.day=today.tm_mday;


      if(fwrite(&new_s, sizeof(struct stock), 1, new_fp)!=1)
{
      printf("Error in writing to new file");
      exit(1);

} /*end if*/
loop++;
return;

} /*end function*/

/*********************************************************************/
/*error()                                                                                           */
/*Parameter:      i. An int to indicate the message required.                   */
/*                        out_prn.      pointer to the printer file                         */
/*                        u.            Pointer to the union.                                     */
/*      Return:            none.                                                                         */
/*                                                                                                       */
/*  A simple routine to display an appropriate error message.             */
/*********************************************************************/


void error(FILE *out_prn, union valid u, int i)
{

      char *e[]={"Error\nError in creation\nError in Delete"};

      fprintf(out_prn,"\t%s\t\t\t%s\n", u.i.cust_code, e[i]);

} /*end function*/

/*********************************************************************/
/*print_headings()                                                                               */
/*Parameter:      out_prn. A pointer to the printer file                         */
/*Return:            none.                                                                         */
/*                                                                                                       */
/*  A function to display the errors for the report.                         */
/*********************************************************************/


void print_headings(FILE *out_prn)
{
      static int page;

      page++;
      bold(out_prn,ON);
    condensed(out_prn, OFF);

      fprintf(out_prn,"\n\tTRANSACTIONS FOR ZENITH PAINTS CO%30.24sPage %3d\n\n"
         "\t\t\t",asctime(todays_date), page);

      fprintf(out_prn,"\tCust Code\t\t\tError Reason\n\n");
      bold(out_prn,OFF);

}/*end func*/