大家好，我是新手，大家能帮我解释一下这个程序么，谢谢啦

#include <vcl.h>
#pragma hdrstop

#include "Unit1.h"
#include "Unit2.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------


void __fastcall TForm1::Button3Click(TObject *Sender)
{
    RichEdit1->Visible=true;
    int iFileHandle;
    int iFileLength;
    //int iBytesRead;
    char *pszBuffer;
   iFileHandle=FileOpen(SaveDialog1->FileName,fmOpenRead);
    iFileLength=FileSeek(iFileHandle,0,2);
    FileSeek(iFileHandle,0,0);
    pszBuffer=new char[iFileLength];
    FileRead(iFileHandle,pszBuffer,iFileLength);
    FileClose(iFileHandle);
    RichEdit1->Text=pszBuffer;[/color]
    delete [] pszBuffer;
    RichEdit1->Visible=False;
    int length,line;
    length=(RichEdit1->Text).Length();
    line=RichEdit1->FindText(Edit1->Text,0,length,TSearchTypes()<<stMatchCase);
    if(line==-1)
    ShowMessage("该用户不存在！");
    else
    {
      if(Edit2->Text=="abc")
      {
      ShowMessage("登录成功！");
      Form2->Show();
      }
      else
       ShowMessage("密码错误！");
    }
 
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
  Edit3->Visible=true;
  Button2->Visible=true;
}
//---------------------------------------------------------------------------

void __fastcall TForm1::Button2Click(TObject *Sender)
{
   if(Edit3->Text!="")
   {
     RichEdit1->Visible=true;
     RichEdit1->Text=RichEdit1->Text+Edit3->Text+" ";
     this->RichEdit1->PlainText=true;
     this->RichEdit1->Lines->SaveToFile(this->SaveDialog1->FileName);
     RichEdit1->Visible=False;

   }
}
//---------------------------------------------------------------------------

void __fastcall TForm1::Button4Click(TObject *Sender)
{
  Close();
}
//---------------------------------------------------------------------------



中的
iFileHandle=FileOpen(SaveDialog1->FileName,fmOpenRead);
    iFileLength=FileSeek(iFileHandle,0,2);
    FileSeek(iFileHandle,0,0);
    pszBuffer=new char[iFileLength];
    FileRead(iFileHandle,pszBuffer,iFileLength);
    FileClose(iFileHandle);
    RichEdit1->Text=pszBuffer;[/color]
    delete [] pszBuffer;
是什么意思！？？？