1. // SquareDemo - demostrate the use of a function
  2. //              which processes arguments
  3. 
  4. #include <stdio.h> 
  5. #include <iostream.h>
  6. 
  7. // square - returns the square of its argument
  8. //          dVar - the value to be squared
  9. //          returns - sqare of dVar
 10. double square(double dVar)
 11. {
 12.     return dVar * dVar;
 13. }
 14. 
 15. int sumSequence()
 16. {
 17.     // loop forever
 18.     int nAccumulator = 0;
 19.     for(;;)
 20.     {
 21.         // fetch another number
 22.         double dValue = 0;
 23.         cout << "Enter next number: ";
 24.         cin  >> dValue;
 25. 
 26.         // if it's negative...
 27.         if (dValue < 0)
 28.         {
 29.             // ...then exit from the loop
 30.             break;
 31.         }
 32. 
 33.         // ...otherwise calculate the square
 34.         int nValue = (int)square(dValue);
 35. 
 36.         // now add the square to the
 37.         // accumulator
 38.         nAccumulator = nAccumulator + nValue;
 39.     }
 40. 
 41.     // return the accumulated value
 42.     return nAccumulator;
 43. }
 44. 
 45. int main(int nArg, char* nArgs[])
 46. {
 47.     cout << "This program sums multiple series\n"
 48.          << "of numbers. Terminate each sequence\n"
 49.          << "by entering a negative number.\n"
 50.          << "Terminate the series by entering two\n"
 51.          << "negative numbers in a row\n";
 52. 
 53.     // Continue to accumulate numbers...
 54.     int nAccumulatedValue;
 55.     do
 56.     {
 57.         // sum a sequence of numbers entered from
 58.         // the keyboard
 59.         cout << "\nEnter next sequence\n";
 60.         nAccumulatedValue = sumSequence();
 61. 
 62.         // now output the accumulated result
 63.         cout << "\nThe total is " 
 64.              << nAccumulatedValue 
 65.              << "\n";
 66. 
 67.     // ...until the sum returned is 0
 68.     } while (nAccumulatedValue != 0);
 69.     cout << "Program terminating\n";
 70.     return 0;
 71. }
 72.