#include <iostream.h>

// file: tempscale.cc
// Processing reals and integers
// convert between Celsius and Fahrenheit

void FtoC(int tempFahr)
{
   cout << tempFahr << " Fahrenheit = "
   << ((tempFahr+40)*5/9 - 40)
   << " Celsius " << endl;
}

void CtoF(double tempCels)
{
   cout << tempCels << " Celsius = "
   << ((tempCels+40)*9/5 - 40)
   << " Fahrenheit " << endl;
}

int main()
{
   int tFahr;
   double dCels;

   cout << "Enter a Fahrenheit temperature ";
   cin >> tFahr;
   FtoC(tFahr);

   cout << "Enter a Celsius temperature ";
   cin >> dCels;
   CtoF(dCels);

   return 0;
}

Sample output:

 <tempscale
<>Enter a Fahrenheit temperature 69
 <69 Fahrenheit = 20 Celsius 
<>Enter a Celsius temperature 20.5
 <20.5 Celsius = 68.9 Fahrenheit 

 <tempscale
<>Enter a Fahrenheit temperature 69
 <69 Fahrenheit = 20 Celsius 
<>Enter a Celsius temperature 20
 <20 Celsius = 68 Fahrenheit 

 <tempscale
<>Enter a Fahrenheit temperature 212
 <212 Fahrenheit = 100 Celsius 
<>Enter a Celsius temperature 0
 <0 Celsius = 32 Fahrenheit