Brauch dringend Hilfe

#include <iostream.h>


int option;
float grad;
float fahrenheit;
float kelvin;
float rankine;
float reaumur;




void main(void)
{
   do
   {
      cout << endl << endl;
		cout << "\tUmrechnung von Temperatureinheiten" << endl;
      cout << "\t----------------------------------" << endl;
      cout << endl << endl;
      cout << "Menueauswahl:" << endl << endl;
		cout << "(1) Celsius in Fahrenheit" << endl;
		cout << "(2) Celsius in Kelvin" << endl;
		cout << "(3) Celsius in Rankine" << endl;
      cout << "(4) Celsius in Reaumur" << endl << endl;
      cout << "Option: ";
		cin  >> option;
      cout << endl;




		if (option == 1)
		{
			cout << "Bitte Temperatur in Celsius eingeben: ";
			cin  >> grad;


         /*Umrachnung Celsius in Fahrenheit*/
         fahrenheit = (((grad * 9 ) / 5 ) + 32);
         cout << endl;
         cout << grad << " Celsius entsprechen " << fahrenheit << " Fahrenheit." << endl;
		}


		else if (option == 2)
   	{
   		cout << "Bitte Temperatur in Celsius eingeben: ";
			cin  >> grad;


         /*Umrechung Celsius in Kelvin*/
         kelvin = (grad + 273.15);
         cout << endl;
         cout << grad << " Celsius entsprechen " << kelvin << " Kelvin." << endl;
		}


		else if (option == 3)
      {
   		cout << "Bitte Temperatur in Celsius eingeben: ";
			cin  >> grad;


         /*Umrechung Celsius in Rankine*/
         rankine = (grad * 1.8) + 32 + 459.67;
         cout << endl;
         cout << grad << " Celsius entsprechen " << rankine << " Rankine." << endl;
		}


      else //(option == 4)
      {
      	cout << "Bitte Temperatur in Celsius eingeben: ";
			cin  >> grad;


         /*Umrechung Celsius in Réaumur*/
         reaumur = (grad * 0.8);
         cout << endl;
         cout << grad << " Celsius entsprechen " << reaumur << " Reaumur." << endl;
      }




      cout << endl << endl;
		cout << "Wollen sie die Abfrage nochmal starten?" << endl;
      cout << "1 = Ja" << endl;
      cout << "2 = Nein" << endl << endl;
      cout << "Entscheidung: ";
		cin  >> option;
   }
   while (option == 1);
}