Найти число Пи методом монте карло

С++ Builder 6 

Компиляция и сборка под Windows 10

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//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"

TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button3Click(TObject *Sender)
{
   if( ComboBox1->Text == "" ){ShowMessage("Выбери число итераций"); return; }

   double iterations=0;
   double x,y;
   double count=0;
   double z;
   double pi;
   
   iterations= ComboBox1->Text.ToDouble();

   srand(time(NULL));

   for (int i=0; i<iterations; i++) {

      x = (double)rand()/RAND_MAX;

      y = (double)rand()/RAND_MAX;

      z = x*x+y*y;

      if (z<=1) count++;
      }
   pi=(double)count/iterations*4;

  Edit1->Text =  FloatToStr( pi ) ;

}
//--------------------только цифры-------------------------------------------------------

void __fastcall TForm1::ComboBox1KeyPress(TObject *Sender, char &Key)
{
if(Key >= '0' && Key <= '9' || Key == VK_BACK ) return;
Key=0 ;
}
//---------------------------------------------------------------------------

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//---------------------------------------------------------------------------

#ifndef Unit1H
#define Unit1H
//---------------------------------------------------------------------------
#include <Classes.hpp>
#include <Controls.hpp>
#include <StdCtrls.hpp>
#include <Forms.hpp>
#include <math.h>

//---------------------------------------------------------------------------
class TForm1 : public TForm
{
__published:    // IDE-managed Components
        TEdit *Edit1;
        TButton *Button3;
        TComboBox *ComboBox1;
        TLabel *Label1;
        TLabel *Label2;
        void __fastcall Button3Click(TObject *Sender);
        void __fastcall ComboBox1KeyPress(TObject *Sender, char &Key);
private:    // User declarations
public:        // User declarations

        __fastcall TForm1(TComponent* Owner);
};
//---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
#endif
 

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