При нажатии на кнопку Button, суммируем значения цифр из Edit.

Код программы:

Unit1.cpp

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



#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::Button1Click(TObject *Sender)

{

Label4 ->Caption=StrToInt(Edit1->Text)+StrToInt(Edit2->Text);

}

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

  Unit1.h

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

#ifndef Unit1H
#define Unit1H
//---------------------------------------------------------------------------
#include <System.Classes.hpp>
#include <Vcl.Controls.hpp>
#include <Vcl.StdCtrls.hpp>
#include <Vcl.Forms.hpp>
//---------------------------------------------------------------------------
class TForm1 : public TForm
{
__published:	// IDE-managed Components
	TEdit *Edit1;
	TEdit *Edit2;
	TLabel *Label1;
	TLabel *Label2;
	TLabel *Label3;
	TLabel *Label4;
	TButton *Button1;
	void __fastcall Button1Click(TObject *Sender);
private:	// User declarations
public:		// User declarations
	__fastcall TForm1(TComponent* Owner);
};
//---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
#endif

StrToInt - Преобразует строку в целое число.