how to use If else stament

[Gatoloco247]

I have to create a earnings yield calculator and here is what I have so far. But i want to be able to calculate when Profit and Shares Outstanding are missing. When I don't any input in Profit and Shares Outstanding I get an error message.

 //declare variables  
			 double EPS;
			 double EY;
			 
			 
			 //if stament to make sure users enters all necessary variables
			 if ((this->tbProfit->Text == String::Empty  ) &&
				 (this->tbSharesOutstanding->Text == String::Empty )&&
				 (this->tbSharePrice->Text == String::Empty) ){
					 MessageBox::Show("Please insert Profit, Shares Outstanding and Shares Price");
			 }
			
			 if ((Convert::ToDouble(tbProfit->Text)&& Convert::ToDouble(tbSharesOutstanding->Text) != 0)&&
				   (Convert::ToDouble(tbSharePrice->Text)&& Convert::ToDouble(tbEPS->Text)!= 0))
			 {
			
				 EPS = Convert::ToDouble(tbProfit->Text)/Convert::ToDouble(tbSharesOutstanding->Text); //Calculates EPS
				 tbEPS->Text = EPS.ToString(".00");
				EY = Convert::ToDouble(tbEPS->Text)/ Convert::ToDouble(tbSharePrice->Text)*(100);  //calculates EY
				tbEarningsYield->Text = EY.ToString(".00");
			   }
				 
				 // else stament to calculate EY if Profit and Shares Outstanding are not giving
				 else 
				 {(Convert::ToDouble(tbProfit->Text)&& Convert::ToDouble(tbSharesOutstanding->Text)!= 0);
				
					 EY = Convert::ToDouble(tbEPS->Text)/ Convert::ToDouble(tbSharePrice->Text)*(100);
			   tbEarningsYield->Text = EY.ToString(".00");
			   }
			 }//ends bnCalculate