Вывести сумму a и b

//---------------------------------------------------------------------------
 
#include <vcl.h>
#pragma hdrstop
 
#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
int a,b,c;
float q,w,f;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------
 
void __fastcall TForm1::Button1Click(TObject *Sender)
{
Close();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::aChange(TObject *Sender)
{
a->Text=" ";
}
//---------------------------------------------------------------------------
void __fastcall TForm1::bChange(TObject *Sender)
{
b->Text=" ";
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button2Click(TObject *Sender)
{
if (a && b)                    //Как мне заставить выводить здесь суму а и b?
{c->Caption=...;}
}
//---------------------------------------------------------------------------

void __fastcall TForm1::Button2Click(TObject *Sender)
{
if (!(a->Text=="") && (b->Text==""))
{c->Caption=a+b;}
}

if ((a->Text!="") && (b->Text!=""))
{c->Caption=a->Text.ToInt()+b->Text.ToInt();}

if( ((a->Text>='0') && a->Text<='9') && ((b->Text>='0') && b->Text<='9')){
  c->Caption=a->Text.ToInt()+b->Text.ToInt();
}