How to change edit control box with button

void operator += (LPCSTR str)
{
	CString CurrText;
        GetWindowText (CurrText);
        if(CurrText!="0")
            CurrText += str;
        else
           CurrText = str;
        SetWindowText (CurrText);
}

void CCalciDlg::OnBnClickedCbutton0()
{
	
	if(eqflg==TRUE)
	{
		SetDlgItemText(IDCRESULT,_T("0"));
		eqflg=FALSE;
	}
	resu += "0";
	
}
void CCalciDlg::OnBnClickedCbutton1()
{
	if(eqflg==TRUE)
	{
		SetDlgItemText(IDCRESULT,_T("0"));
		eqflg=FALSE;
	}
	resu += "1";
}
void CCalciDlg::OnBnClickedCbutton2()
{
	if(eqflg==TRUE)
	{
		SetDlgItemText(IDCRESULT,_T("0"));
		eqflg=FALSE;
	}
	resu += "2";
}
void CCalciDlg::OnBnClickedCbutton3()
{
	if(eqflg==TRUE)
	{
		SetDlgItemText(IDCRESULT,_T("0"));
		eqflg=FALSE;
	}
	resu += "3";
}
void CCalciDlg::OnBnClickedCbutton4()
{
	if(eqflg==TRUE)
	{
		SetDlgItemText(IDCRESULT,_T("0"));
		eqflg=FALSE;
	}
	resu += "4";
}
void CCalciDlg::OnBnClickedCbutton5()
{
	if(eqflg==TRUE)
	{
		SetDlgItemText(IDCRESULT,_T("0"));
		eqflg=FALSE;
	}
	resu += "5";
}
void CCalciDlg::OnBnClickedCbutton6()
{
	if(eqflg==TRUE)
	{
		SetDlgItemText(IDCRESULT,_T("0"));
		eqflg=FALSE;
	}
	resu += "6";
}
void CCalciDlg::OnBnClickedCbutton7()
{
	if(eqflg==TRUE)
	{
		SetDlgItemText(IDCRESULT,_T("0"));
		eqflg=FALSE;
	}
	resu += "7";
}
void CCalciDlg::OnBnClickedCbutton8()
{
	if(eqflg==TRUE)
	{
		SetDlgItemText(IDCRESULT,_T("0"));
		eqflg=FALSE;
	}
	resu += "8";
}
void CCalciDlg::OnBnClickedCbutton9()
{
	if(eqflg==TRUE)
	{
		SetDlgItemText(IDCRESULT,_T("0"));
		eqflg=FALSE;
	}
	resu += "9";
}
void CCalciDlg::OnBnClickedCbuttonpoint()
{
	CString msg;
	GetDlgItemText(IDCRESULT,msg);
	if(flg==TRUE)
	{
		msg=msg+'.';
		SetDlgItemText(IDCRESULT,msg);
		flg=FALSE;
	}
	pctrl.EnableWindow(FALSE);
	//SetProperty(IDCBUTTONPOINT,WS_VISIBLE,FALSE);
	
}
void CCalciDlg::OnBnClickedCbuttondiv()
{
	num=0;
	opflg=4;
	UpdateData(TRUE);
	num=num1;
	SetDlgItemText(IDCRESULT,_T("0"));
}
void CCalciDlg::OnBnClickedCbuttonmul()
{
	num=0;
	opflg=3;
	UpdateData(TRUE);
	num=num1;
	SetDlgItemText(IDCRESULT,_T("0"));
}
void CCalciDlg::OnBnClickedCbuttonplus()
{
	num=0;
	opflg=1;
	UpdateData(TRUE);
	num=num1;
	SetDlgItemText(IDCRESULT,_T("0"));
}
void CCalciDlg::OnBnClickedCbuttonminus()
{
	num=0;
	opflg=2;
	UpdateData(TRUE);
	num=num1;
	SetDlgItemText(IDCRESULT,_T("0"));
}
void CCalciDlg::OnBnClickedCbuttonequal()
{
	eqflg=TRUE;
	
	if(num1!=0)
	{
		UpdateData(TRUE);
		switch(opflg)
		{
		case 1:
			num=num+num1;
			break;
		case 2:
			num=num-num1;
			break;
		case 3:
			num=num*num1;
			break;
		case 4:
			num=num/num1;
			break;
		case 0:
			AfxMessageBox(_T("Please Select The Operation"),MB_OK);
			break;
		}
		CString str;
		str.Format(_T("%.2f"), num);
		SetDlgItemText(IDCRESULT,str);
		resu.SetSel(0,-1);
	}
	else
	{
		AfxMessageBox(_T("Enter The Second Value"),MB_OK);
	}
}