Urgent help please

[SephirothSPR]

Runtime Error :

void Movie::show_movie(int k){
    system("cls");
    struct detail *mv;
    FILE *f;
    int n;
    f = fopen("data.dat","ab+");
    fseek(f,0,SEEK_END);
    n=ftell(f)/sizeof(detail);
    mv = new detail[n];
    fseek(f,0,SEEK_SET);
    fread((char*)&mv, sizeof(detail), n, f);  //I think the error occurs here
    fclose(f);
    cout << "\n\n\t\t\tName\t\t\tStart On\t\t\tStart At";
    for(int i=0; i<n; i++)
    cout<<"\n\n\t\t"<<mv[i].name<<"\t\t\t"<<mv[i].start_date<<"/"<<mv[i].start_month<<"/"<< mv[i].start_year<<"\t\t\t"<<mv[i].start_hour<<":00 - "<<mv[i].end_hour<< ":00";
    cout << endl << endl;
    delete[] mv;
    cout << "Press any key to return to previous menu...";
    getch();
    cout << endl << endl;
    if(k==0) movie_menu();
    if(k==1) admin_menu();
}

[upX86]

what is the file size?

[SephirothSPR]

I have solved the problem by reading the structure 1 by 1 instead of reading whole n structure. :)

[SephirothSPR]

But couldn't we read them all at once?

[coder777]

But couldn't we read them all at once?

Yes, but you need to provide the correct size. On line 11 you provide the size for a single object.

[dhayden]

Yes, but you need to provide the correct size. On line 11 you provide the size for a single object.

I think the code is correct in that respect. The fread() is reading n objects of size sizeof(detail).

But it's reading it into the wrong place:

struct detail *mv;
...
mv = new detail[n];
...
fread((char*)&mv, sizeof(detail), n, f);  //I think the error occurs here 

The fread is storing the data at mv's address. In other words, it's overwriting the pointer itself (and a whole lot more). You want to store the data in the location that mv points to:

fread(mv, sizeof(detail), n, f);

No need to cast to a char* since fread expects a void* as its first argument and any pointer will cast automatically to void*