Fahrenheit to Celsius Conversion

Write a program that reads in a temperature in
Fahrenheit from the user, and prints out the
equivalent in Celsius.  If Tf is the Fahrenheit
value and Tc is the Celsius value, here's the
conversion rule: Tc = (Tf - 32.0)*(5.0/9.0)
Note: There's a tricky point in C++ that makes it
important to use the ".0" for your doubles.  It
all comes down to the idea of types!
#include "si204.h"

int main() {
  // Read temperature in Fahrenheit
  double Tf;
  fputs("Enter temperature in Fahrenheit: ", stdout);
  Tf = readnum(stdin);

  // Compute temperature in Celsius
  double Tc;
  Tc = (Tf - 32.0) * (5.0/9.0);

  // Write temperature in Celsius
  fputs("That is ", stdout);
  writenum(Tc, stdout);
  fputs(" degrees Celsius.\n", stdout);

  return 0;