Сортировка массива структур (файловый ввод/вывод)

//---------------------------------------------------------------------------
 
#include <vcl.h>
#pragma hdrstop
#include <math.h>
#include "Unit1.h"
#include<stdio.h>;
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
typedef struct {
    char fio[20];
    }TStudent;
TStudent Stud[100];
int nzap=0;
FILE *Fs;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
 
}
//---------------------------------------------------------------------------
 
 
void __fastcall TForm1::Button5Click(TObject *Sender)
{
fclose(Fs);
}
//---------------------------------------------------------------------------
 
void __fastcall TForm1::Button1Click(TObject *Sender)
{
strcpy(Stud[nzap].fio,Edit1->Text.c_str());
Memo1->Lines->Add(AnsiString(Stud[nzap].fio));
fwrite(&Stud[nzap],sizeof(TStudent),1,Fs);
nzap++;
}
//---------------------------------------------------------------------------
 
void __fastcall TForm1::Button2Click(TObject *Sender)
{
OpenDialog1->Title="Naw File";
if(OpenDialog1->Execute())
{
 char *FileNameS= OpenDialog1->FileName.c_str();
  if((Fs=fopen(FileNameS,"wb"))=NULL) {
  ShowMessage("File no created");
  return;}
}
}
//---------------------------------------------------------------------------

if((Fs=fopen(FileNameS,"wb"))=NULL)

if((Fs=fopen(FileNameS,"wb"))==NULL)