動作環境

C++ Builder XE4
RAD Studio 10.2 Tokyo Update 2 (追記: 2017/12/28)

イベント開始後の経過秒数を表示したい。

TStopwatchを使ってみた。

参考 http://www.gesource.jp/programming/bcb/110.html

以下が必要
- #include <System.Diagnostics.hpp> //
- #include <TimeSpan.hpp> //

Unit1.h

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

# ifndef Unit1H
# define Unit1H
//---------------------------------------------------------------------------
# include <System.Classes.hpp>
# include <Vcl.Controls.hpp>
# include <Vcl.StdCtrls.hpp>
# include <Vcl.Forms.hpp>
# include <Vcl.ExtCtrls.hpp>

# include <System.Diagnostics.hpp> //
# include <TimeSpan.hpp> //
//---------------------------------------------------------------------------
class TForm1 : public TForm
{
__published:	// IDE で管理されるコンポーネント
	TTimer *Timer1;
	TLabel *Label1;
	TButton *B_start;
	TButton *B_stop;
	void __fastcall Timer1Timer(TObject *Sender);
	void __fastcall B_startClick(TObject *Sender);
	void __fastcall B_stopClick(TObject *Sender);
	void __fastcall FormClose(TObject *Sender, TCloseAction &Action);
private:	// ユーザー宣言
	TStopwatch m_stopwatch;
public:		// ユーザー宣言
	__fastcall TForm1(TComponent* Owner);
};
//---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
# endif

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)
{
	m_stopwatch = TStopwatch::Create();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Timer1Timer(TObject *Sender)
{
	int elpsd_sec = m_stopwatch.ElapsedMilliseconds / 1000;

	String msg = IntToStr(elpsd_sec);
	Label1->Caption = msg;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::B_startClick(TObject *Sender)
{
	m_stopwatch.Reset();
	m_stopwatch.Start();

	Timer1->Interval = 1000;
	Timer1->Enabled = true;
}
//---------------------------------------------------------------------------

void __fastcall TForm1::B_stopClick(TObject *Sender)
{
	Timer1->Enabled = false;

	m_stopwatch.Stop();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormClose(TObject *Sender, TCloseAction &Action)
{
	m_stopwatch.Stop();
}
//---------------------------------------------------------------------------

m_stopwatchという１つのインスタンス変数で管理できるのは利点かもしれない。