Can you help me debug this c++ program [update a file]?

#include "stdafx.h"


#include %26lt;stdio.h%26gt;


#include %26lt;stdlib.h%26gt;


#include %26lt;ctype.h%26gt;


#include %26lt;conio.h%26gt;


#include %26lt;string.h%26gt;





struct book


{


char bookID[6];


char title[31];


char author[31];


char copyright[5];


}bookrec;





FILE *bookfile;





int main()


{


bookfile= fopen("BOOK.DAT", "rb");





if(bookfile==NULL)


{


printf("File does not exist, press any key..");


getch();


}


else


{


fread(%26amp;bookrec, sizeof(bookrec), 1, bookfile);


if(feof(bookfile))


{


printf("File is empty, press any key..");


getch();


}


else


searchNupdate();


}


fclose (bookfile);





return 0;


}





void displayTitle(void)


{


printf("\n\t\t==UPDATE A FILE==\n");


printf("\t\t==BOOK==\n");


printf("UPDATE RECORDS:\n\n");


}





void dispRec(void)


{


printf("%s%s%s%s\n",bookrec.bookID,bo...


}





void displayRecord(void)


{


int lineCounter=0;





while(!feof(bookfile))


{


displayTitle();





while(lineCounter%26lt;10 %26amp;%26amp; !feof(bookfile))


{


dispRec();


lineCounter++;


fread(%26amp;bookrec, sizeof(bookrec), 1, bookfile);


}


if(!feof(bookfile))


{


printf("Press any key to continue..");


getch();


}


else


printf("End of file, press any key..");


getch();


}


}





void updateRecord(void)


{


char nBookid[6];


char nTitle[31];


char nAuthor[31];


char nCopyright[5];


int field;


char rep;





do


{


printf("Which field to update[1-4]? :");


scanf("%d", %26amp;field);





while(field%26gt;4)





if(field==1)


{


printf("Input new book ID:");


gets(nBookid);


}


else if(field==2)


{


printf("Input new book title:");


gets(nTitle);


}


else if(field==3)


{


printf("Input new book author:");


gets(nAuthor);


}


else


{


printf("Input new copyright:");


gets(nCopyright);


}





do


{


printf("Update another field(Y/N)? :");


scanf("%c", %26amp;rep);


}


while(tolower(rep)!='y' %26amp;%26amp; tolower(rep)!='n');





} while(rep=='y')


fseek(bookfile, 1, 0);


fwrite(%26amp;bookrec, sizeof(bookrec), 1, (bookfile));


fclose(bookfile);


}





void search(int target[6],int found, int size)


{


int found=0, i;


int count=0;


int field=0;





bookfile= fopen("BOOK.DAT", "r+");


fread(%26amp;bookrec, sizeof(bookrec), 1, bookfile);





while(!feof(bookfile) %26amp;%26amp; found!=0)


{


if(target[i]==field)


{


found=1;


}


else


{


count++;


fread(%26amp;bookrec, sizeof(bookrec), 1, bookfile);


}


}


size= count * sizeof(%26amp;bookrec);


}





void searchNupdate(void)


{


char rep, target[6];


int size=0;


int found=0;





displayTitle();


do


{


printf("Input book ID to be updated:");


gets(target);





search(target,%26amp;found,size);





if(!found)


{


printf("Record is not found\n");


}


else


{


displayRecord();


}


do


{


printf("Update (Y/N)? :");


scanf("%c", %26amp;rep);


}


while(tolower(rep)!='y' %26amp;%26amp; tolower(rep)!='n');


if(rep=='y')


{


updateRecord(%26amp;size);


}


do


{


printf("Update another (Y/N)? :");


fflush(stdin);


scanf("%c", %26amp;rep);


}while(tolower(rep)!='y' %26amp;%26amp; tolower(rep)!='n');


}


while(rep=='y');


fclose(bookfile);


}

Can you help me debug this c++ program [update a file]?
Can you give a hint on what function the error occurred?